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September 2

Compiler Writing: NOT Parser Generators!

I search for compiler writing tools or compiler-compilers on Wikipedia and on Google and when I look at their websites it says they are parser generators (and are used for making domain-specific languages for analysis, not general-purpose languages which I want to do, might I add) and make no mention of compiling SDFs or whatever into compilers! It is driving me nuts. Is "parser generator" just some fancy term for compiler among compiler-writing developers or am I missing something? Is there a good tool out there for Windows that I can use to make compilers (open source, BSD or other permissive license, preferably)? --Melab±1 ☎ 01:04, 2 September 2010 (UTC)

A Lexical analyzer and a parser are two major components of a compiler. The other major component is the logic of what to do with the tokens after they've been parsed. That part will pretty much have to be written by a human.

Luckily for anyone crazy enough to want to do this, this is a common "final project" for C.S. majors, so there are books and stuff on how to do it. (Personally, I opted out and wrote a video game instead.) I make no claims for the quality of either of these two sources (Like I said, I skipped this.) , but this seems to get good reviews, and some folk seem to be very impressed by this older (but probably still mostly valid) guide on the same topic. APL (talk) 02:57, 2 September 2010 (UTC)

Programs are (conceptually) tree-like things, but, because of the human mind's amazing facilities with language, it turns out to be best to represent those trees in a linear fashion, as text, in languages that are (approximately) context-free languages. Turning the text back into a tree is considered a solved problem (though there's still a little bit of research in that area!), and that's what "compiler-compilers" or "parser generators" do. But a compiler is really something that translates from one language to another, and that part is a classic programming task that's best left in the hands of humans.

There are two things that any prospective compiler writer must think about:

• Can an interpreter do the same job? For a lot of tasks, interpreting a language is easier than compiling it, and the speed penalty isn't worth worrying about.
• What's the best destination language? Someone has to write a compiler that takes programs to assembly language, but most people don't need to. It's far easier to compile to a pre-existing language with a good implementation. Taking this philosophy to an extreme, the macros in Lisp or (especially) Scheme amount to a tower of gradually-more-powerful languages, each compiled down to the next with an incredibly simple compiler. Common destination languages include C and LLVM, but compiling down to a high-level language like Haskell or Scheme or C++ or ML is also done.

Paul (Stansifer) 04:25, 2 September 2010 (UTC)

There's no reason you need to re-invent the parser every time you want to invent a new compiler. Parsing is the boring task of sophisticated string tokenization. There's not much to improve or innovate there - it's just a necessary, difficult, and boring part of machine text analysis. Instead of re-inventing this (and similar parts of the compiler), learn to use the already existing Flex and Bison. (Our articles may be the best place to start). These tools do the grunt work of text analysis, leaving the compiler design to you. The real meat-and-potatos of compiler design is the sophisticated process of defining your high-level language into a structured form describable by (for example) Backus-Naur form. That is the first step. Once in this kind of intermediate representation, the second step (mapping BNF to a set of machine instructions) is very pedantic. You should not waste your time re-designing that second mapping (especially if you are unfamiliar with the 900 or so instructions available on a modern Intel CPU, or other CPU architecture of your choice).

Furthermore, using standard tools means that you can plug in your language to existing systems. A lot of compilers for many different languages use the same back-end, so that they can focus on design for their language instead of for the instruction set architecture of the machine(s) they are targeting. For example, almost all of the compiler tools in the gcc kit (C, FORTRAN, Delphi, Pascal, ... and on and on and on) all use the same gcc back-end structure. This way, your Delphi and your Pascal and your C++ program can all run through the same hardware-optimization routines (and so on). (...totally and irrefutably invalidating any claim about any programming language that inherently yields "better performance" or "faster code" - but I digress).

Anyway, if you really want, you can re-invent these steps; nothing stops you from writing your own parser and lexical analyzer. You can also code a compiler in assembly language; and you can also redefine a character encoding that uniquely re-interprets machine binary representations as characters of your choice, (ASCII has many shortcomings), and you can write your own text-editor and character-mode video driver that can understand your homebrew text-encoding. There is a certain line you have to draw - decide the tradeoff between how much time you want to spend re-inventing things, and how much time you want to spend learning the existing tools. Nimur (talk) 04:34, 2 September 2010 (UTC)

Responding to your small text: there are many reasons why some languages yield smaller or faster machine code independently of the backend. For example, C doesn't specify the effect of an out-of-bounds array access. This means that an array read or write can legally be compiled down to a single indexed read/write at the machine level. Most other languages require that the index be checked against the array's upper and lower bounds (which must also be loaded from memory) and a certain exception be raised if the test fails. A correct optimizer can't drop the bounds tests unless it can prove they will always succeed (or always fail). In many cases that can't be proven because it's false, and even when it's true, proving theorems is hard even for human mathematicians and it's even harder to program a computer to do it (with useful efficiency). The best you can probably hope for is optimizing away the tests in a simple loop like for (i = 0; i < x.Length; ++i) { ... }, but even that may fail if there's a function call in the body, because it may be hard to prove that the function won't modify x's length. The programmer apparently expects it not to, but programmers are often wrong and optimizers have to preserve program semantics.

There are lots of other examples like this. In an untyped language it's hard to optimize away the extra runtime type checks. In a language with powerful runtime reflection and/or a powerful eval statement, you can't inline any function because you can't prove that it won't change at runtime. In this old thread I listed a few reasons why it's hard to efficiently compile Java and Java-like languages. Aliasing is another interesting example. A C89 compiler must assume that any two pointer expressions of the same type may alias each other unless it can prove otherwise. FORTRAN prohibits aliasing of arrays, which makes automatic vectorization easier. This is one of the reasons why FORTRAN dominated numerical computing for so long. C99 added the restrict keyword to enable optimizations that assume no aliasing. -- BenRG (talk) 23:57, 2 September 2010 (UTC)

Maybe "irrefutable" was an overly-strong word... : ) You are right, and you bring up some cases (like exceptions-handling, and pointer mangling, and function inlining, and garbage-collection) that are language-specific and could limit performance. But for many (actually, for almost any code other than numerical data-processing kernels), these optimizations have minimal impact on wall-clock execution time. The most important optimizations - substituting machine-architecture (ISA) enhancements to replace long streams of common instructions - work on code generated from any source-language. For example, GFortran translates all FORTRAN code to GIMPLE, and then runs the exact same GIMPLE optimizer as it generates machine code, (so whether your program is C++ or Java/gcj, gccwill automatically compile in SSE and 64-bit operations if your computer supports them). So exactly those optimizations you talk about - like handling pointer aliasing and so on, can be handled in a source-language-invariant way (unless the language specifically interferes with these optimizations). Overlapping arrays are the best example of a case where the language-specification will actually enable or forbid certain optimizations (like out-of-order execution on pointer operations); if the language guarantees these can not exist, the compiler is free to do fancy things. But, outside of sophisticated vector-math numerical kernels, how many programs meaningfully reap the benefit of OOE array operation optimizations? (It should be noted that even ifort defaults to assuming aliasing - probably because unless you manually specify -fno-alias, it runs through a "C-language" style optimizer that refuses to make the assumption that arrays are "safe", which is specific to FORTRAN). Here's the User Guide for IFORT, with more information than you ever wanted about optimized compilation. Nimur (talk) 00:28, 3 September 2010 (UTC)

Backing-up to a NAS drive over the Internet?

I would like to be able to attach a drive to my mum's router at home so that my computer away at University will be able to back-up via the Internet (updating the back-up to reduce the total file transfers). Is this possible, though? I contacted one or two companies a while ago, and I believe that their responses were that their NAS drives would allow back-up via the local network but not via the Internet. --89.243.142.40 (talk) 01:14, 2 September 2010 (UTC)

I believe that remote access to the NAS is possible, but you will need to configure your router to allow it. First, please note that any changes to the allow outside access into the home network represents a security risk, so you need to make sure that the proper security features (i.e. passwords) are enabled on the NAS device. I assume that your home has a typical network that includes some kind of modem (cable, ASDL, or similar), which is connected to a router, which in turn has wired and/or wireless connections to the other devices (computer(s), NAS device, etc.) in the home.

What is commonly referred to simply as a router also provides firewall and network address translation (NAT) features which act as a bridge between your private home network (LAN) and the rest of the internet (WAN). Inside your home network, devices have locally distinct IP addresses typically of the form 192.168.xx.xx, assigned by the router. However, your internet service provider will only assign a single IP address to the model, such as the 89.243.142.40 address we see in your original post. This is the address that the rest of the internet sees.

Normally, any computer inside your private network (or LAN) can initiate a connection out to the internet (the WAN), but any unsolicited attempts from the outside to connect into your network are refused. NAT serves to keep track of what's connected to what, so when one computer sends out a request, the response is routed back to the requesting computer. However, when an inbound connection request is received, the router does not automatically know which local device should receive the request, so the request is dropped. Port forwarding allows you to configure your router to send specific connection requests to specific devices, to send all requests to a designated device (sometimes called the DMZ, or a combination. Port numbers generally identify the type of internet connection request. For example, port 80 is HTTP, which you might want to route to your computer if it were running a web server. Port 21 is generally used for FTP and you may wish to configure your router to forward such requests to your NAS. (You may have already set up some port forwarding if you use some internet games.) You will need to check your router's documentation to see in detail how to configure fort forwarding. You will also need to check your NAS documentation to identify what ports and protocols are supported, and of course how to set up the security.

Port forwarding also allows you to translate port numbers, called port translation. For example, you may wish to map inbound port 8080 to port 80 in your local computer and map inbound port 12345 to port 21 on your NAS. Sometimes this is necessary because many ISPs block certain well known ports to discourage customers from running home based servers. It also allows you to assign an arbitrary number to the service to make it less likely that a hacker will detect your server using port scanning techniques.

The final key that you will need is the IP address of the home network. Ideally, it remains static over time, but ISPs generally do not guarantee this, and it may change after a power or service outage. I believe there are some services out there that allow you to periodically post the home's current IP address so that you can look it up remotely, but someone else will need to fill in these details. Once you have port forwarding configured and know the home IP address, you can remotely access the NAS as something like "ftp://89.243.142.40/" or "ftp://username:password@89.243.142.40:12345/" (where "username" and "password" are what you configured in your NAS security setup and ":12345" identifies your externally defined port). From this point you need to look at your backup software to see how to configure it to connect to your distant NAS.

Good luck. I'm sure others can fill in any missing details and correct any error in the above. -- Tom N (tcncv) talk/contrib 04:10, 2 September 2010 (UTC)

I use TeamViewer to remotely access my home PC. It allows file transfers. Not sure it it supports backups as such. ---— Gadget850 (Ed) ^talk 15:37, 2 September 2010 (UTC)

Re: changing IPs above, a simple solution would be to use one of the many free domain name with dynamic DNS support service. Many routers come with support for updating a dynamic DNS built in, if yours doesn't you can either install software on your mothers computer (should be easier but will obviously only work when your mothers computer is on) or since I believe many NAS devices use some sort of specialised Linux or similar you could probably install something on your NAS (if your NAS doesn't come with it built in, they may I don't know much about NAS). If you're using FTP there may be a bit more work to get it working properly however Nil Einne (talk) 08:40, 3 September 2010 (UTC)

This Type of Image

Kindly have a good look at this type of Image. Please note that my question is not about the format but the style of the image. Such images are perhaps (if I am not wrong) only found on Wikipedia. What I find intriguing as an artist is easy way with which the contrasts of colors is played upon to fool the human eye, which is very-very difficult effect to achieve even digitally let alone with brush. What I'd like to know is what this movement in computer-art is known, what tool is typically used to conjure up this kind of stuff ( I don't think its GIMP). If there is a history behind this movement, i.e. who invented it etc. Are there any Wikipeople out there who are Gurus etc.  Jon Ascton  (talk) 05:57, 2 September 2010 (UTC)

This is a vector image; it uses gradient fill (specifically, radial gradients), which are part of the SVG vector image format specification, to define the smooth color blends. This same effect can be done using GIMP on raster-images; though in this case, InkScape was used. The style could be considered pop art, but it's hard to classify. These images aren't only found on Wikipedia; but this particular image comes from a freely-licensed icon set; so it is advantageous for use on Wikipedia. You can find stylistically similar icons and logos in many other free and non-free projects.Nimur (talk) 06:12, 2 September 2010 (UTC)

I would emphatically dispute classifying it as Pop art, unless you take the perspective that everything is Pop art. A quick look at the Pop art article makes it clear how different it is; it has really nothing in common except a very broad modernist base. --Mr.98 (talk) 11:33, 2 September 2010 (UTC)

Ok, I am not an art critic, so I don't know the definitions well! I see bright colors, bold lines, and stylized cartoonish figures; but if that is not "pop art" in the ordinary definition, then I am mistaken in my classification! Nimur (talk) 20:54, 2 September 2010 (UTC)

Pop art qua Pop art is defined not so much by its appearance as by its intentions. The article discusses this quite well. It's about using the visual language of popular commodities and moving them into a high art context. So it's Andy Warhol painting Campbell's soup cans, as a way of saying, "look, I'm making art by mimicking advertisements," or Roy Lichtenstein making fake "comic book" panels, saying, "look, this wouldn't normally look like art except for the fact that I am blowing it up and claiming it is art," and so on. The general aesthetic I think you are meaning is just modernism more broadly — generally simplistic, often (but not always) basic colors, appeals to function rather than ornate form, stripped down, etc. E.g. Bauhaus or late Piet Mondrian and so forth. I'm not an art critic either, but Pop art is the wrong category altogether. --Mr.98 (talk) 22:14, 2 September 2010 (UTC)

Obviously it is a vector image, and the GIMP and Photoshop specialize in raster images. It would actually be quite easy to draw such an image in an illustration program such as Adobe Illustrator. You draw three squares. Then, you stack them on top of each other and use the Pathfinder palette to make them cut into each other. Then, you go to Effect --> 3D --> Extrude & Bevel. The light above was probably added by drawing a white circle over the shape and then lowering its opacity.

It would be even easier to construct that shape in a dedicated 3D program like Autodesk Maya, where you can add lights. It would look more realistic, as well.--Best Dog Ever (talk) 06:16, 2 September 2010 (UTC)

Which, by the way, would ruin the stylistic effect of that nice icon. Comet Tuttle (talk) 06:26, 2 September 2010 (UTC)

Irrelevant. My point is simple: the drawing is simply three squares and a circle that have been transformed. It is true that it would take a lot of skill for a human to draw that. But it was drawn by a computer. The drawing program only sees three squares and a circle with a list of tranformations. (At least, that's how it would be represented in PostScript after being drawn by Adobe Illustrator.) The work was done mostly by a computer, and it did it with ease.--Best Dog Ever (talk) 06:38, 2 September 2010 (UTC)

This is quibbling now, but saying "the work was done mostly by a computer" is false. This was created by a computer artist who utilized some software as a tool to create the image. Comet Tuttle (talk) 15:22, 2 September 2010 (UTC)

The general look of the image, with its radial gradients and soft beveling, is generally modeled after the iconography that became popular "Aqua" styles used by Apple, Inc.. (see, e.g., their logo, Mail.app icon, Safari's icon). It has since been copied/emulated/improved upon/etc. by Windows (Windows Vista's Aero theme is an obvious descendant), and a number of Linux themes (like the icon you posted there, from KDE). If you Google "Apple icon effect" you can find many tutorials; it is not very hard to accomplish with their a raster or vector editor. --Mr.98 (talk) 11:33, 2 September 2010 (UTC)

See Computer_icon, icon design, and Graphical user interface elements.Smallman12q (talk) 01:09, 4 September 2010 (UTC)

Difference between SIMD and Vector Processors

What is the exact difference between SIMD and Vector processors?

Is there any difference from computation philosophy?

I worked with few processors where 'data parallelism' is implemented by following two methodologies:

(1) Some processors(MIPS, SNE) have some instructions to treat a 32bit register as 'a set of 4( or 2) 8bit( or 16bit) independent elements' and operate over them. Vendors of such processors call it as SIMD.

(2) Some processors(SiliconHive, SPI) have special 256bit registers( vector register) and instructions to operate over these vector registers treating it as 'a set of 16 16bit elements'. Vendors of such processors call it as vector processor

Other than these increased element number, is there any difference between SIMD/Vector processing ?

—Preceding unsigned comment added by ArpanH (talk • contribs) 11:27, 2 September 2010 (UTC)

The terms are generally interchangeable. SIMD is a more specific description of how a processor operates on a vector. "Vector processor" just indicates that the processor is aware of vectors (groups) of data. Since the typical purpose for treating separate data as a single vector is to use the same operation on all of it, most vector operations are SIMD operations. Nimur (talk) 16:09, 2 September 2010 (UTC)

Conventional Explosives Simulation Software

Hi.

   Is there any software (whether open-source, freeware or commercial) which can be used to simulate the deformation and detonation of an explosive warhead? This software should be able to accept input of shape, size, dimensions, mass, etc. of both the explosive filler and the warhead-wall; and output the following numerical values.

• Total Blast Radius
• Lethal Blast Radius
• Brisance

   The software must support designing with the following 22 explosives:

1. Mercury Fulminate
2. Triazidotrinitrobenzene
3. Triaminotrinitrobenzene
4. Dinitrodiazenofuroxan
5. Trinitroaniline
6. Trinitrobenzene
7. Trinitrotoluene
8. Nitroglycol
9. Tetranitroglycoluril
10. Nitroglycerine
11. Mannitol Hexanitrate
12. Pentaerythritol Tetranitrate
13. Cyclotrimethylenetrinitramine
14. Cyclotrimethylene Tetranitramine
15. Hexanitrohexaazaisowurtzitane
16. Octanitrocubane
17. Nitroguanidine
18. Nitrocellulose
19. Ammonium Nitrate
20. Methyl Nitrate
21. Urea Nitrate
22. Lead Azide & Silver Azide

   Basically, now I'm looking for a free-form explosive warhead design software. Thanks to everyone. Rocketshiporion♫ 12:11, 2 September 2010 (UTC)

r u a terrorist? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 13:29, 2 September 2010 (UTC)

You're looking for open source software to design a warhead? I refer you to the answers to your similar question above about looking for open source software to design a nuclear weapon. Comet Tuttle (talk) 15:21, 2 September 2010 (UTC)

He/She wants to simulate an explosion with software. 82.44.55.25 (talk) 15:53, 2 September 2010 (UTC)

If you want to animate an explosion, here are some tutorials: Object Explosion for 3D Studio Max, and Large Scale Explosions for Blender (software). If you want to accurately simulate, then the responses to your previous question still apply. If you really want to research this stuff, consider applying for an advanced technical degree program at a school that studies energetic materials. For example, New Mexico Tech is a science and engineering research university with a specialty in energetic materials. But they won't just hand out information, software, and material support to anybody - because this stuff can be very dangerous. The process of building credibility in these kinds of areas is long and slow and subject to regulation. Nimur (talk) 16:23, 2 September 2010 (UTC)

I should clarify; I already have the relevant information (for most of the above-mentioned explosive compunds) with which to calculate blast radii. I currently have to manually calculate the blast radii based on the RE factor and mass (and shape, in the case of a shaped-charge) of the explosive filler. What I need is just a software into which I can plug the equations for each of the above explosive compounds, in order to automate the process of calculating blast radii, and thereafter animate the explosion. Rocketshiporion♫ 18:15, 2 September 2010 (UTC)

So go use a spreadsheet, then. Masked Booby (talk) 02:45, 3 September 2010 (UTC)

Cyclotrimethylenetrinitramine? You have some pretty potent stuff there...are you looking to make an accurate simulation of this type of military grade explosives? What exactly with and why?Smallman12q (talk) 01:14, 4 September 2010 (UTC)

Mini-flash cookie app

Based on Steve Baker's question above and my reply... Does anyone know of a very tiny flash app that I can put on a web page and then save/fetch cookies through javascript? It would be best if it was a rather invisible little one-pixel app that could be shoved into a corner of the page and not hinder the rest of the page design. The goal is to save cookies in one web browser and fetch those same cookies in another web browser on the same computer. -- kainaw™ 12:14, 2 September 2010 (UTC)

Be easy to make one yourself; [1] [2] ¦ Reisio (talk) 16:28, 3 September 2010 (UTC)

broadband numbers

my isp gave me these numbers for my broadband

   34.2                   -15.4              49.8   

they said -15.4 was very bad. what do these numbers mean? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 13:28, 2 September 2010 (UTC)

Did they really not explain further? The first thing I thought they were were speeds, but I'm not sure. Chevymontecarlo 14:15, 2 September 2010 (UTC)

What's the ISP? From looking at them, I'd guess they're downstream signal-to-noise levels measured in decibels. 82.44.55.25 (talk) 14:33, 2 September 2010 (UTC)

Yeah, probably. I'm going to guess you have a cable modem, and not DSL. If those are cable modem signal levels, the -15.4 is probably your downstream power level, which is a bit outside the recommended range. If you research it a bit (look up your cable modem model number), you can probably figure out how to check these stats directly on your cable modem's configuration page. DSL modems have transceiver statistics, which look similar, but afaik they don't usually have any negative numbers. Indeterminate (talk) 16:11, 2 September 2010 (UTC)

The poor signal power probably indicates that either you are far away from their networking equipment, or that the cable connection is degraded or has many splits. This is something the cable provider needs to handle; there is nothing you can do about it. Nimur (talk) 16:27, 2 September 2010 (UTC)

Javascript wait

Resolved

I'm trying to write a script for greasemonkey that autofills a box. However the box doesn't appear for 5 seconds after the page loads. Is there a "wait" command in javascript that could pause the script for 5 seconds before continuing? 82.44.55.25 (talk) 18:15, 2 September 2010 (UTC)

Write one function that waits with a timeout and another function that does the work. The timeout requires the function name of the second function and will have the syntax: window.setTimeout("yourSecondFunction()", 5000); // 5000 is how many microseconds to timeout for. -- kainaw™ 18:18, 2 September 2010 (UTC)

Thanks. What would be the function name of

document.getElementsByName("input")[0].value = "Hello";

82.44.55.25 (talk) 18:52, 2 September 2010 (UTC)

You can place that direction into the timeout as: window.setTimeout("document.getElementsByName('input')[0].value = 'Hello';", 5000); Keep an eye on those quotes. I changed to single quotes inside the double quotes to avoid escapes. -- kainaw™ 19:10, 2 September 2010 (UTC)

Thanks! 82.44.55.25 (talk) 19:21, 2 September 2010 (UTC)

NP theory

sir, I have been through ur article about NP,NP-Complete and NP-HARD definations and problems but i can't understand the defination of NP-HARD class And the difference between NP complete and NP hard .

What do u mean by "at least as hard as the hardest problems in NP" please explain elaborately !!!!!!!!!! —Preceding unsigned comment added by A khan0001 (talk • contribs) 18:37, 2 September 2010 (UTC)

All NP problems are decision problems. They have an answer: Yes or No. There are many examples. The NP-Complete ones are the difficult ones and they all have the same solution. For example, if I give you a 3-SAT problem, you can rewrite it as a Travelling Salesman problem and then solve the Travelling Salesman problem to solve the 3-SAT problem that I gave you. NP-Hard problems include NP-Complete problems, but much more. NP-Hard is an intersection with NP. NP-Hard includes decision problems and optimization problems. So, consider this: "Is there a way to travel over all the bridges in town without crossing a single bridge twice?" The answer is Yes/No, so it is in NP. It can be NP-Hard also (if it is NP-Complete). Consider this: "What is the shortest route that crosses all bridges in town without crossing a single bridge twice?" The answer is a route, not Yes/No, so it is not in NP. It is an optimization problem. It is at least as hard as the previous decision problem. So, if the original decision problem is NP-Complete, this is NP-Hard. -- kainaw™ 18:43, 2 September 2010 (UTC)

Wait a minute, not all Yes/No problems are NP, and the "vice versa" part is only formal.

For example, the problem "does a given Turing machine halt?" has a Yes/No answer, but it's not NP. It's not even decidable by a fixed algorithm. See halting problem.

For the converse, yes, it's easier to do some formal manipulations when you restrict your attention to Yes/No problems, but NP is "morally" more general than that. For example, "factor a given number into primes" is NP in every way except purely formally. --Trovatore (talk) 18:53, 2 September 2010 (UTC)

I was purposely being general because this questioner appears to still be at the "I don't understand the difference between an NP and NP-Hard problem" stage. To many details leads to confusion, not clarity. -- kainaw™ 18:55, 2 September 2010 (UTC)

Do you think that flat wrong answers lead to "clarity"? Your answer was not even in the right direction; it was not helpful whatsoever. --Trovatore (talk) 19:04, 2 September 2010 (UTC)

Also, factoring into primes is not in NP for two reasons. First, it isn't a decision problem. Second, it is not verifiable in polynomial time because verifying extremely large numbers are truly prime is a difficult problem. The second step of understanding NP that I normally go to is verification of the answer. It must be simple to verify. That is why the halting problem is not NP. If you say "no, it won't halt", how can I verify that answer in polynomial time? -- kainaw™ 18:59, 2 September 2010 (UTC)

Factoring into primes can be rephrased as a decision problem, in such a way that a polynomial-time answer to one gives you a polynomial-time solution to the other, and vice versa. Something like "given n and k, is the k'th bit from the right of the smallest prime factor of n equal to 1?".

As for your second point, that's less trivial, but in fact it is now known that it is possible to decide in polynomial time whether a given number is prime. If that weren't the case, we could still talk about "factoring" in general being NP, I think, just not "factoring into primes" (it would require more care in the statement).

Your last point is correct, but you didn't say anything about it in the response to the OP, which made your answer completely useless. --Trovatore (talk) 19:10, 2 September 2010 (UTC)

Actually, for (the decision version of) factoring into primes being NP, you don't need primality testing to be in P. It is sufficient to know that it is in NP, and this has been shown two almost three decades before AKS (and it's much simpler to prove).—Emil J. 10:18, 3 September 2010 (UTC)

Simply put, an NP-hard problem is at least at hard as the hardest problems in NP, but it may be (much) harder and therefore not itself in NP; an NP-complete problem is NP-hard and is in NP. An NP-complete problem is a hardest problem in NP. --98.114.98.162 (talk) 04:32, 3 September 2010 (UTC)

Typing credit card details into SLL-enabled CGI proxies

Is it safe? If not, is creating a bypass proxy a safe way of doing it (as described in this tutorial: http://www.erasparsa.com/Create-Your-Own-CGI-Proxy-to-Bypass-the-Great-Firewall-of-Indonesia). Thanks in advance --Mark PEA (talk) 19:58, 2 September 2010 (UTC)

I only checked the first script on that page, and that one apparently (according to its readme) offered you a form in which you can type an URL. I wouldn't trust any proxy of that type with confidential data. If the other CGIs work the same way - a form, as opposed to allowing you to set it as a proxy server in your browser - they'd be unsafe too. A proper proxy allows your browser to use the CONNECT verb (see Hypertext Transfer Protocol) for SSL, and then simply passes along the data without being able to see it. As long as you verify the SSL certificate and you trust the issuer, and as long as your browser hasn't been tampered with, such connections should then be secure. 82.75.185.247 (talk) 22:07, 2 September 2010 (UTC)

An SSL proxy would mean that the proxy would see your data...the SSL means that the traffic to the proxy is encrypted, but it doesn't mean the proxy is trustworthy.Smallman12q (talk) 01:17, 4 September 2010 (UTC)

So I assume it is something like: Me -> Proxy (HTTP), Proxy -> Website (HTTPS). Is there no way of getting a Me -> Proxy (HTTPS) connection? --Mark PEA (talk) 17:36, 4 September 2010 (UTC)

I think you misunderstand...it goes like this: You->SSL(Proxy SSL)->Proxy->SSL(website SSL)->website. If I understand correctly, what you want is to be able to securely access a website(that is also secure)...see Tunneling_protocol, Virtual_private_network, and Secure_Shell. Provided your proxy is actually secured, you shouldn't be susceptible to a Man-in-the-middle attack. Hope this helps.Smallman12q (talk) 22:45, 4 September 2010 (UTC)

Compressing

Resolved

I'm want to compress around 90,000 .mht files. I'm using 7zip with the solid compression option, which works extremely well. I've read about solid compression being susceptible to corruption, for example if one part of the file is damaged everything after it also becomes unsalvageable. Would setting the "solid block" size lower to something like 1GB secure against complete failure? If part of the file got damaged, would only the parts in that "block" be unsalvageable, but files in other blocks would be ok? Is that how sold compression blocks work? 82.44.55.25 (talk) 20:11, 2 September 2010 (UTC)

Yes. If you're worried about corruption, some PAR2 parity files will protect you better than limiting the block size. -- BenRG (talk) 00:03, 3 September 2010 (UTC)

Just make redundant backups. ¦ Reisio (talk) 02:32, 3 September 2010 (UTC)

Actually depending on how many redundant backups you create and in what form, some sort of parity files may be better. I personally prefer ICE ECC [3] although it's closed source so may not be a good solution long term Nil Einne (talk) 13:04, 4 September 2010 (UTC)

For such a specific question, I think the best answer to your question is going to actually come from experimentation. Try compressing 1000 files, using two different block sizes, then use a hex editor to overwrite part of each file with a bunch of random digits, identically, then see what happens when you try to decompress. The experiment won't take long. Comet Tuttle (talk) 15:37, 3 September 2010 (UTC)

I did a few experiments and lowering the block size drastically improves recovery. I also discovered there is very little difference in compression size between full solid mode and 16mb block mode, so obviously 16mb blocks is best the way to go. Thanks! 82.44.55.25 (talk) 18:38, 3 September 2010 (UTC)

Domain Names

Is it possible to find all the domain names that a given company have registered? Thanks Mo ainm~Talk 20:23, 2 September 2010 (UTC)

You could use this Reverse Whois which searches by owner name, but it's not free. It does give you an idea of how many domains *might* be owned by your search parameters (before you have to pay), but there's no real way of being sure that a company is using the same name for all it's domains, sub domains might be registered to smaller sister-companies or there might even be simple things like spelling errors in the owner name when it was registered. Also it wouldn't work with any domains that are using a domain privacy service to cloak the Whois information as it would literally point to the cloaking service with a reference code and wouldn't contain the company name.  ZX81  ^talk 20:59, 2 September 2010 (UTC)

e-mail account hijacked

My wife had her Yahoo e-mail account hijacked today. Apparently everybody in her address book (except me) got a message saying she had been robbed and was stranded in London airport and could you please wire £1500 immediately. As soon as she was able she went in and changed the password and security questions in her account.

This doesn't appear to be e-mail spoofing; one friend wrote back and asked the perpetrator for the names of two dogs. In the response one answer was actually right (our daughter's dog, dead for three years).

The question is: what happened? Did someone actually get into the account? She said some profile fields were changed. If so, how could that have happened? Did they get the password? Also, having changed the password, how safe is she now? Thanks, --Halcatalyst (talk) 22:31, 2 September 2010 (UTC)

Some possible reasons are:

• she used the same password for something else, or the password was something too obvious (the name of her kid, or dog, or favourite band)
• her password was too poor, and a bulk script (probably running on a botnet) guessed it
• she left herself logged in on a public machine (e.g. at the library)
• her normal machine is compromised by malware
• she logged in on another machine (web cafe, library) which was compromised by malware
• she used an insecure login method (yahoo! mail does login by default over ssl, so that'd be an odd reason) over a public wireless network (e.g. at a cafe)
• she donated, lost, or had stolen a computer, pda, phone, or backup, and someone recovered the password from it (this is quite possible, but in practice fairly unlikely)
• she got a crooked email, or visited a crooked website, which directed her to a site constructed to closely mimic Yahoo! Mail, but that was in fact the spammers'.

They probably know the name of the dog because they searched the email account for "dog" when interrogated.

Sensible things to do:

• have a genuinely secure password
• don't use the same password for multiple things (except for trivial things that you don't care about, and definitely don't use the trivial-things password for something important like shopping, banking, or email)
• just don't type your password into a public machine at all, or into any machine you don't absolutely trust. If you need to be mobile, setup a phone or laptop to check email, and use that.
• make sure you use SSL for login
• keep your own computers properly maintained, with up-to-date and effective anti-virus and anti-malware software. Practice caution when installing software. Don't allow incompetent people or those with poor judgement the ability to administer the same machine you use for work, banking, or an email account that you've registered with anything important (if they control the email, crooks can have shopping or banking sites reset your password, which is emailed to them, so they've leveraged email access into something more valuable).

-- Finlay McWalter ☻ Talk 23:07, 2 September 2010 (UTC)

Another wise thing: only visit an important site like email or banking from a URL you typed in yourself, or from a link you've stored on your own computer (e.g a bookmark or a desktop shortcut). Never click on a link on some site that purports to take you to Yahoo!Mail, in case it's a malicious spoof instead. -- Finlay McWalter ☻ Talk 23:24, 2 September 2010 (UTC)

And (just to scare you more) they might have done something like this (all with a script, all very fast, trying many many options):

• get access to the email account (by some method above)
• search the email account for mails from financial institutions (FIs) - banking, pensions, stocks, investments
• from these, visit the FI's website and try to login with the password they know. If that fails, do a password-reminder
• the FI emails the Yahoo! account the reminder or temp-password, which they use to login. Only the security questions are stopping them now: how good are her answers? Is her pet's name given as "Fido" or "h!fP9+3J>Q7"? If they have access to the email account, they can search it for clues (pets, kids, favourite places)
• transfer monies away
• delete the password reminder email(s) to cover their tracks a bit (even a few hours will be enough for them to forward the stolen money on through a maze of compromised or untraceable accounts).

-- Finlay McWalter ☻ Talk 23:18, 2 September 2010 (UTC)

While I'm not denying the importance of keeping your email secure, if your bank has a reset password by email option, I suggest you get a new bank before doing any of the above Nil Einne (talk) 15:52, 6 September 2010 (UTC)

She may also have somehow visited a "phishing website" that appeared to be a Yahoo login screen, but was REALLY just a false front that sent her password to the scammers. (It may have actually forwarded her to the real Yahoo website so she wouldn't notice anything was wrong.)APL (talk) 02:24, 3 September 2010 (UTC)

September 3

Idiotic and Useless Emails

Why I keep on getting more and more foolish messages like proposals to get quick money (100000 $) ! etc. from a bank etc. who account holder is dead or other bullshit like that. Who is behind all this and what they gain by wasting people's time ?  Jon Ascton  (talk) 01:11, 3 September 2010 (UTC)

Have you ever heard of a phishing trip? (Now that I read that joke a couple times, it sounds really corny...) Essentially, some slob sitting in a smelly apartment somewhere is hoping you're dumb enough to hand over your most sensitive financial information. Then, they can then use it to ring up something expensive and/or illegal, or sell it to someone else who will end up doing that anyway for thousands of dollars. Of course you wouldn't hand over your credit card number for no good reason, so they cook up all sorts of crazy schemes to dupe you. Most often I hear about the Nigerian prince scam that asks you to wire money to a sketchy Nigerian "prince" so he can send you a ridiculous amount of money in return. Other suspicious e-mails include: you have won a lottery you never entered, and the company needs your bank details so they can send you the winnings; the legitimate-looking e-mail from your bank telling you that you have to change your bank website password for some reason; or there is some rich foreigner who died in a plane crash with no will or family, and you have been chosen to receive his fortune. Ignore them. It's a huge business, and many people are suckered in. You can protect yourself by just deleting them, and remembering that there is no such thing as free money. Xenon54 (talk) 02:14, 3 September 2010 (UTC)

Or set up a filter that puts mail with words like 'free money' into junk.Sir Stupidity (talk) 03:22, 3 September 2010 (UTC)

There are several of these scams out there and people fall for them every day. I read an article a couple years ago about a woman who kept giving more and more money away to someone on the net in the hopes of an eventual pay off. If I remember correctly, she gave the scammer something like US$14,000. Dismas|^(talk) 04:38, 3 September 2010 (UTC)

There was an elaborate scam attempt on me the other day. I offered a cellphone for sale online in South Africa, and this person claiming to be on holiday in London wanted me to post the cellphone to his son working in an oilfield in Nigeria. Just the mention of Nigeria set off an alarm bell and I refused to give him my banking details... he even offered way more money than I was asking. Obviously this sounded too good to be true so I told him to transfer into my paypal account. Soon after I got a very authentic looking email from "paypal" but first of all, my paypal status wasn't updated and after looking at the email more carefully, I noticed the odd spelling mistake and the wrong email account being used. It was also sent by someone@gmail on behalf of services@paypal. I reported it to paypal who said they would investigate. I can imagine some derelict warehouse in Nigeria receiving thousands of free items a day and the police there just turning a blind eye. Just be careful people... even worse than material theft is identity theft... it can wreck your life. Sandman30s (talk) 06:00, 3 September 2010 (UTC)

The basics of the scam have already been clearly outlined. The scammers work on a model that expects a tiny fraction of people that fall for it - The vast majority of people will simply delete the email. However, as in the case mentioned by Dismas - when the phishers do get a 'bite' they can be in for a significant prize. If it really does annoy you, there are a number of sites set-up that give advice to people about trolling the scammers, and they also publish transcripts of the trolling communications (some can be quite funny). If you do go down that route though, be careful not to give the scammers any personal information that could be used to steal your ID Darigan (talk) 11:23, 3 September 2010 (UTC)

So why do you keep getting these foolish emails, while I haven't received any spam in months? Because I don't go spreading the email addresses I really care about all over the internet. I tell friends and relatives my real email address, I use several webmail accounts for signing up to site memberships and shopping (places that might sell my address onto a third party), and I use other webmail accounts for very occasional 'dodgy' dealings with places that will definitely sell my address onto a third party. Also, I never reply to any spam, even to request they 'unsubscribe' me. The net result is that the spam ends up in an account I only visit once or twice in 6 months, and my real address gets no spam. Astronaut (talk) 11:39, 3 September 2010 (UTC)

It's really important never, ever, to reply to spam. There is a possibility that a spammer receiving any sort of reply could make him notice that the e-mail address is live, which encourages him to send even more spam to it. Because of a similar reason, the e-mail client I use (Evolution) by default does not automatically download images in HTML e-mails. If it did, the spammer's HTTP server would register a connection from my IP address, confirming that the spam was received by a live person. So Evolution is clever enough to prevent that. JIP | Talk 19:16, 3 September 2010 (UTC)

I know the 'never respond' advice is often given. but has this ever been confirmed to (still) be true? If you have a botnet capable of sending mail to a 100 million email addresses, is a spammer actually bothering to send his second spam run to only a fraction of those? Unilynx (talk) 10:03, 4 September 2010 (UTC)

I find I receive junk e-mails with nonsensical contents and subject lines, with an attached image. I've never opened one of the images, but I wonder what this is about. --rossb (talk) 19:32, 4 September 2010 (UTC)

Is the image attached, or just embedded? If it's just linked to you can be sure that they're doing it to test for valid email addresses. (As soon as your mail client sends a request to the server the image is on, they know the email went through.)

If it's actually attached, it may not be an image. Sometimes you see files named things like

"NakedGirls.jpg                                                            .exe"

If it's attached, and if it's legitimately an image file, then I'm mystified. I don't think I've ever gotten one of those. APL (talk) 00:06, 5 September 2010 (UTC)

It may well be an attempt to get around Bayesian spam filters. The image can contain a picture of the word "Viagra" (as well as the name of their website) without tripping any filter conditions. Marnanel (talk) 15:18, 5 September 2010 (UTC)

One time I was in a mood to click a link that promised free iPhone. iPhone was indeed free, but to qualify for it web site required to sign up for number of "promotions", like half a dozen out of forty available, and each of them was non free, requiring products purchase or payments for services. Since I obviously did not trusted the site, I haven't purchase anything, but I clicked couple links that I found interesting (one was Disneyland something, important for later developments). And at the beginning I filled the form with my real address in it(but phone number thanx god was fake, duh! should have gave them local police station number!). Next thing a couple months or so later I received backpack full of toys, addressed - opps had to go, finish later. 70.52.186.74 (talk) 00:06, 5 September 2010 (UTC)

Addressed "TO: Mynamehere's child" A small backpack itself and toys looked very cheap, but were delivered to my address. Then a letters start coming into my mail, with requirements to pay for it. Sum was not big, less then $50, forty something. And letters looked scary - basically they were saying, you owe us for service/goods provided, please make a payment or call number to pay with credit card etc. And I got something from them! And it was smart on their side, backpack arrived long time I visited a site, and how many people would remember what they were doing online and exact wording of what they signed up for couple month ago while they were browsing online bored? I was even considered myself to make a payment (now it sound silly, but then, when I was reading letters - it just looked like it is better to pay rather then get into some kind of trouble). Anyway I did not paid a cent and, afraid, backpack ended up in the garbage bin, since I had no use for it. What amazes me, is that those truly random website phishers did invested some real money into products (cheap one, but anyway), and bothered themselves with not only electronic phishing. And I bet, if I would provide them with my real phone number, I would have get some automatic system calling my cellphone every other day to remind about payment and such. And in case I have paid them, they could have sent me another gift "worth" $200+. Hope you like this story. 70.52.186.74 (talk) 02:18, 5 September 2010 (UTC)

data corruption

Resolved

Is there a way to simulate data corruption on a file? Like a special program that can corrupt a file to varying levels so you can test how much the data is retrievable? 82.44.55.25 (talk) 09:47, 3 September 2010 (UTC)

A hex editor may be the simplest to use for your basic tests. If you want to be systematic, a simple program should be easy to write; you just have to define "corruption". For example, consider three different kinds of failures:

• "zero out 1 byte at 1024 uniformly-distributed random locations in the file"
• "zero out 1024 bytes, starting at file-offset 100,000."
• "zero out every 8th byte, starting at file-offset 0, and ending at file-offset 8192"
• "xor 1024 bytes in the file using the same bitmask."

These all corrupt the same number of bytes in file, but each simulate a different kind of failure-mode. Unless you know how your files might get corrupted, it's difficult to simulate (or to design a good strategy for recovery). Consider reading our error detection and correction article. Nimur (talk) 18:06, 3 September 2010 (UTC)

Thanks! 82.44.55.25 (talk) 18:35, 3 September 2010 (UTC)

Parchive

I've read the Parchive article but I don't understand how it works. It makes indexes of file hashes which can be used to repair files? How exactly is that done? What level of damage can the file be before the Parchive can't fix it? 82.44.55.25 (talk) 09:56, 3 September 2010 (UTC)

It uses a parity bit system. Parity relies on xor which is a bit operation. Just like addition is 1+1=2 and represented by a +, xor is a bit operator and is often represented with a ⊕, or a ^ in some programming languages. Xor is "one or the other but not both." So 0⊕0=0, 1⊕0=1, 0⊕1=1, 1⊕1=0.

If you're storing something, let's say a string of 1's and 0's (1100 0010). You can split it up into two blocks, then compute a third block, a parity block. So you then store 1100, 0010, and 1110 (the last one is your parity block). Now if any one block gets clobbered somehow, you can figure out what it was using the remaining blocks. If two or more get clobbered, you're out of luck.

This is the general idea. It can be expanded, applied to millions of strings like that, etc. That's how parity systems work. You might find RAID-5 interesting, it works on the same principal. Shadowjams (talk) 23:20, 3 September 2010 (UTC)

I want to point out that my explanation isn't exactly how parchive works either. It uses Reed Solomon codes which entail more detail. [4] That is the original paper that the theory's based on. But the general idea is still the same. Shadowjams (talk) 23:36, 3 September 2010 (UTC)

The general concept is called an erasure code. 67.122.211.178 (talk) 01:01, 6 September 2010 (UTC)

Webpage to PDF

Is there anything that can easily turn a webpage into a PDF? I have seen the the Firefox add-on 'PDF Download' but it is tagged as Adware, does the conversion online, and has had bad recent reviews. Thanks 92.15.11.118 (talk) 10:17, 3 September 2010 (UTC)

My Firefox allows me to print (File -> Print) to a file, and I can select PDF as the output file. Does this suit you? --Ouro (blah blah) 11:13, 3 September 2010 (UTC)

My computer (WinXP) does not offer that unfortunately. 92.15.11.197 (talk) 14:04, 3 September 2010 (UTC)

If you want something that can do it in batch (for example to snapshot a website regularly) wkhtmltopdf works well.-- Q Chris (talk) 11:23, 3 September 2010 (UTC)

That looks interesting but as Windows has deskilled me so that I only understand clicking something, I do not know how to set it up or run it. 92.15.11.197 (talk) 14:08, 3 September 2010 (UTC)

For this purpose, I installed CutePDF Writer, which does the same thing that Ouro above describes on my Windows XP system. Comet Tuttle (talk) 14:56, 3 September 2010 (UTC)

In an unexpected turn of events, I cannot check how it works, no Linux version. Sidenote, I wonder why FF for Win does not give the option to print to a PDF file. Hope Comet's solution works out for you. --Ouro (blah blah) 16:23, 3 September 2010 (UTC)

"print to file" is part of the standard desktop printing architecture in many desktop Linux distributions. It works just the same as the pseudo-printer that CutePDF installs. It's available to any desktop program that's aware of printing (strictly I think there's one plugin for Gnome and a different one for KDE, but they work much the same); they're mostly a layer built on Ghostscript. Non-gui programs have to call Ghostscript themselves to do the same job. -- Finlay McWalter ☻ Talk 16:33, 3 September 2010 (UTC)

Could be. Has to be out of the box, this install is fresh (done last week) and almost nothing had been modified because I didn't have the time to do it. On Ghostscript, I remember yeaaaaaars ago (in the days of W98SE) I had to install Ghostscript to do... a lot, print to files too I think... Thanks. --Ouro (blah blah) 16:39, 3 September 2010 (UTC)

I use PDFmyURL. It does exactly what it says on the tin - type your URL into the box and it provides a PDF to download. It does add a logo to the PDFs though. Equisetum (talk | email | contributions) 17:15, 3 September 2010 (UTC)

Quite a silly thing to do. If you merely want to archive a web page into a single file, use Mozilla Archive format (for Firefox, Internet Explorer has its own built-in which does the same thing). ¦ Reisio (talk) 02:09, 5 September 2010 (UTC)

Your assumption is wrong. Thanks for the gratuitous put-down. In any case I tried that in the past, then uninstalled it because it wasnt very good. 92.15.30.74 (talk) 12:56, 5 September 2010 (UTC)

It was a charity — any other thing you might be wanting to do other than merely archiving a web page to a single file... would be even sillier (using PDF). ¦ Reisio (talk) 19:09, 6 September 2010 (UTC)

If you're running OS X, the Print function (File --> Print) has a feature that does exactly this - in the Print window of Safari (or Firefox) there will be a 'PDF' button in the lower-right. Select it, and then "Save as PDF". Rishi.bedi (talk) 18:02, 8 September 2010 (UTC)

a/b drives

why do my computer does'nt have a, b drives —Preceding unsigned comment added by Shantanuca (talk • contribs) 10:43, 3 September 2010 (UTC)

These are usually assigned to floppy drives. If your computer doesn't have a floppy drive, then those drive letters won't be shown 82.44.55.25 (talk) 10:57, 3 September 2010 (UTC)

See Drive letter assignment. It's sad that people are already forgetting floppy disks; it makes me feel old. In any case, what happens if you have more drives than letters to assign? Do you start getting drives AA, AB, etc., or does the computer just not let you do it. Buddy431 (talk) 13:28, 3 September 2010 (UTC)

I asked a question about that a while ago, Wikipedia:Reference_desk/Archives/Computing/2010_May_2#Drive_letters 82.44.55.25 (talk) 13:42, 3 September 2010 (UTC)

That's interesting, thanks. Buddy431 (talk) 01:17, 4 September 2010 (UTC)

FWIW, MS-DOS v2 (released in 1983, and I now feel old) certainly used to let you go on beyond Z, so the next drive would be [:, and so on through the ASCII set. I don't know when this was removed. Marnanel (talk) 14:58, 5 September 2010 (UTC)

Javascript time

I want to write a greasemonkey script that will popup an alert box at a certain time, say 6pm. Sort of like an alarm clock. In javascript, is there a way to make a function execute at a set time? 82.44.55.25 (talk) 11:08, 3 September 2010 (UTC)

The window.setTimeout function will launch a function after a specified number of milliseconds. Calculate the number of milliseconds between now and 6pm. Then, use that number of milliseconds as the offset for setTimeout. -- kainaw™ 12:43, 3 September 2010 (UTC)

Cell Phone and Lap top

I am thinking about purchasing a cell phone and contract that will allow me about 800 anytime minutes free on weekends and evenings. (perhaps a variation, free incoming) I also want to be able to retrieve email and brouse Web. I can get such a plan for about 60.00 a month. I would then like to cancel my home internet and home phone. I only want to do this if I can plug in the new phone to my lap top and be able to read my email on the lap top and to hopefully write emails on the lap top that will be sent back through my cell phone. DOES ANYONE KNOW IF THIS IS POSSIBLE. ANY ADVICE IS APPRECIATED. I AM GOING OUT TO DO SOME HANDS ON TESTING BUT HAVE NO IDEA WHAT WOULD BE THE BEST PLAN OR PHONE. I DO SEEM TO FAVOUR THE SLIDE KEY BOARD FOR TYPING TEXTS. A bigger phone screen would also be helpful for reading texts etc. —Preceding unsigned comment added by 99.199.47.107 (talk) 17:06, 3 September 2010 (UTC)

Where are you? Your IP address suggests you're in Canada. -- Finlay McWalter ☻ Talk 17:21, 3 September 2010 (UTC)

What you're wanting to do is called tethering. Most smart phones can do it in some way or another. You will want to check with your mobile provider to see what options they offer for mobile broadband tethering. Most mobile broadband plans are designed with the idea that access is solely through your phone. Thus, most providers charge extra for this service. Also, keep in mind that mobile broadband plans are usually more restrictive in terms of bandwidth and data caps. If you're just utilizing the Internet for email, you shouldn't have a problem. However, if you're wanting bandwidth intensive applications (video, gaming, etc.) you are going to see poor performance compared with wired Internet access. --—Mitaphane _{Contribs | Talk} 18:31, 3 September 2010 (UTC)

Methods for multiple classes

I'm trying to write a math thing in Java where there is a fraction class, a radical class, a polynomial class, and so on. When defining multiplication for fractions, I would multiply the numerator and the denominator, but there could be many things in the numerator, like an polynomial or a radical or something. First, how would i declare the class of the numerator, and second, could i write something saying "call the multiply method of whichever class this belongs to"? KyuubiSeal (talk) 21:44, 3 September 2010 (UTC)

There are several ways you can do this. Off the top of my head:

1. You just have each type of math thingy implement multiply functions for all the things it's meaningful to multiply it by. Java's polymorphism mechanism will call the right one. So your Complex class might have a multiplyBy(Integer) method, a multiplyBy(Complex) method and so forth. This is the straightforward way to go - a (probably minor) downside is that if you add a new kind of math thingy you need to alter all the things it can multiply by so that they know about it, and you have to do that at compile time.
2. If you needed extensibility beyond that, you can dispatch calls through a dynamic registry you maintain. That way you can add (even at runtime) new math thingies, but the code gets rather complex. Have all these math thingies be concrete implementations of an abstract base class (lets say MathThingy). MathThingy has a multiply(MathThingy A, MathThingy B) method. This is final. When this is called, it uses getClass on its arguments, looks them up in a little registry, and calls specific methods in the concrete subclasses. The registry is filled by the class constructors of each MathThingy as they're classloaded - so the Complex class registers handler methods that say they can handle intXcomplex, complexXint and complexXcomplex. This is very flexible - you can even add new operators (at a logical level; java doesn't allow you to overload or define actual java syntax operators). But a major downside (aside from the complexity) is that type errors become runtime errors rather than compile time ones (so you don't get a problem saying you can't raise a complex number to the power of a matrix until you run the program).

-- Finlay McWalter ☻ Talk 22:08, 3 September 2010 (UTC)

I get the first part about the polymorphism already, but I suppose I should rephrase my question. If I have a Fraction class, it would have an attribute numerator, right? How could I make the numerator an instance of the Polynomial or Radical or BigInteger class? And when it is, is there a way I could say numerator.multiply(5), and have it call the correct class's multiply(int)? Also, how is there no operator overloading, but "a"+"b" will give "ab"? Is that just a special case? KyuubiSeal (talk) 23:07, 3 September 2010 (UTC)

In your example, you need "Polynomial or Radical or BigInteger" or "..." to satisfy either option:

• implements a common interface, like "Multipliable", or
• extends a common parent class, like "MathematicalExpression"

The first way uses a Java interface, and you can follow this tutorial to learn how to use it. The second method uses inheritance - follow this tutorial to learn how to use it. The two methods are subtly different. Now, you can specify your numerator to be a "Multipliable" or a "MathematicalExpression" - and any class that either implements that interface (or extends that parent-class) is acceptable to use as a Numerator. Then, when you call a multiply() method, it will use the implementation of that method for the actual runtime type of the object. Nimur (talk) 23:33, 3 September 2010 (UTC)

Lastly, your question about Strings: these are "special things" in Java. Consider them a "special case" - they are true objects, but they are the only objects in Java that permit Operator Overloading (and this is the cause of much debate and brouhaha - but was part of the language design). Note that the language explicitly specifies this syntax - and it is not actually "operator overloading," it is special shorthand Java syntax for a new String constructor. This is to make the language "easy to use" for text processing, while staying true to certain "Java commandments" about object-oriented design. (And, take it from a seasoned programmer: you do not want operator overloading. You think you want operator overloading, but that is because you don't have it and haven't seen how horrible it is). Nimur (talk) 23:40, 3 September 2010 (UTC)

(we're rat-holing here, so I won't belabour this too much) when people say they "do not want operator overloading" I've found they mostly mean the brain-damaged operator overloading that C++ inflicts on innocent minds. Haskell's operator definition (I won't insult it by calling it overloading) lets you define type, arity, priority, and fixity (and actually deigns to let me define any operator I want, like foo or ⊕ or !!!) and combined with Haskell's non-shit type system makes for operator definition to work the way you'd sanely want it to. Sorry for the digression, as KyuubiSeal is working in an environment without such luxuries. -- Finlay McWalter ☻ Talk 01:12, 4 September 2010 (UTC)

So if I have a variable of class A (or interface B), any subclass of A (or something implementing B) can be assigned to it? This means anything can be assigned to an Object, right? And would there be any casting involved? (That's probably not too difficult to handle though) KyuubiSeal (talk) 23:55, 3 September 2010 (UTC)

Yes, you can assign an object of a subclass to a reference of any of its superclasses. And the system remembers what type it really is - so if you later upcast it (Java will make you handle a ClassCastException in this case) it's still of the same type you defined it as. The java instanceof is your friend here - you can say "is X an instance of A, or is it an instance of B, or not", and act accordingly. -- Finlay McWalter ☻ Talk 00:57, 4 September 2010 (UTC)

Okay, it's working now. Thank you so much! KyuubiSeal (talk) 01:09, 4 September 2010 (UTC)

Terminal window of safari

Where can I find the terminal window of Safari 5.0.1? I want to do some tweaking.Thanks--180.234.39.169 (talk) 23:22, 3 September 2010 (UTC)

Safari does not have a terminal; are you sure you don't mean either the operating system's terminal or the Safari Snippet Editor or Error Console ? Nimur (talk) 23:26, 3 September 2010 (UTC)

• How can I open terminal window?--180.234.39.169 (talk) 07:25, 4 September 2010 (UTC)

If you mean your operating system's "terminal" window, try to navigate to /Applications/Utilities and double-click on Terminal. If you still can't find it, see this.--Mithrandir^∞ (Talk!) (Opus Operis) 07:31, 4 September 2010 (UTC)

September 4

Recovery of Deleted File on SD Card

Help!

   I accidentally deleted a .zip file from a Secure Digital card. The file is about 275KB in size, and was deleted before a backup could be made. In order to stop the deleted data from being overwritten, I have made the SD card read-only by using the write-protect switch. The SD card's filesystem is NTFS, and my operating-system is Microsoft Windows 7 Professional Edition. I need to recover the deleted file ASAP - is there any free software or freeware I can use to recover my deleted file?

   Any and all help is appreciated, and thank you to everyone.

I don't know offhand what the windows software is but there is Linux software to do the same thing. There are Live Discs that do the same thing. It's likely your file's recoverable. Write protecting it is the right idea. I'm sure others will know of some windows software. Shadowjams (talk) 07:13, 4 September 2010 (UTC)

PhotoRec and Recuva both come highly recommended and can undelete basically anything as long as it hasn't been over-written. Good luck! Zunaid 07:17, 4 September 2010 (UTC)

What is the cellular 3G base station price range?

If someone want to cover around 5,000 km2 with 3G coverage - what amount of investment into cellular hardware he will be looking at? Assuming wired data network is already exist and installation costs for towers are out of scope of this question(and spectrum licenses out of scope too). One million users inside 5.000 km2. Basically, how much one base station roughly cost and how big would be the cell it will cover? Was trying to search Google, but no luck so far. —Preceding unsigned comment added by 70.52.186.74 (talk) 07:31, 4 September 2010 (UTC)

I don't know about the cost, but the number of base stations would depend on the specific mobile technology and frequency used, the local geography and the amount of bandwidth required. The table in this article suggests a CDMA-2000 network operating at 1800 MHz has cells 14 km in radius (each covering an area of ~600 km²). However, considering how close the mobile masts are in my area of the UK, I think that might be an idealised radius. Indeed, OFCOM's Mobile phone base station database indicates that a city of 100,000 people has well over 50 base stations and a city the size of Manchester has nearly a 1,000 base stations. Astronaut (talk) 08:46, 4 September 2010 (UTC)

Thank you! You actually shifted my keywords selection toward right direction and I found an article that mention number of base stations to cover Germany: they have more than 20.000 GSM base station covering 99% of the population and 13.000 UMTS base stations covering 80% of the population. That is perfect for my purposes. Still wondering about rough price estimation that cellular companies pay for base stations(preferably 3G)... 70.52.186.74 (talk) 11:15, 4 September 2010 (UTC)

Some more searches - and I found an answer! Thanks a bunch! If not you, I would still be wondering. I also think that number of base stations for Manchester is that high because there is different cell companies operate there while some stations are shares, most are not or support different types of network(like GSM vs CDMA and such). And another interesting number - total base station in UK is ~53 000... 70.52.186.74 (talk) 11:39, 4 September 2010 (UTC)

AFAIK all mobile phone networks in the UK use GSM or it's 3G decendents (UMTS etc) Nil Einne (talk) 13:00, 4 September 2010 (UTC)

The numbers I mentioned above are from a database that is aimed at people concerned about radiation exposure from mobile comms. Therefore it lists the number of masts in an area and lets you see the frequency, signal strength and company/companies on each mast (interesting because I found out why there is a dead spot round my sister's house :-) If only one operator is in an area of flat geography, then maybe fewer masts will be required, but you would still need sufficient capacity to support the bandwidth your 1 million population might use. Astronaut (talk) 23:47, 4 September 2010 (UTC)

Scanning over the network

The charity where I volunteer recently bought a new printer/copier/fax/scanner (a Xerox Workcenter 4118). It has a builtin network card which is connected to the rest of the network using a standard ethernet cable, and a standard telephone connection is used so faxes can be sent and received. However, reading the user manual it seems the scanner function can only be used if it is connected a USB or parallel cable. Is there a way to get scanning to work across the network using any PC on the network, perhaps using a third-party piece of software? Being an underfunded charity, there is a strong preference for a low price, or better still, free solution. Thanks. Astronaut (talk) 08:12, 4 September 2010 (UTC)

Go to Start --> Control Panel --> Scanners and Cameras --> Add Device --> Xerox --> Next. Then, right-click on the scanner and choose Properties --> Xerox Settings --> Add and then enter the IP address of the scanner. After scanning, double-click on the scanner, and WIA should reveal any scanned documents.--Best Dog Ever (talk) 08:24, 4 September 2010 (UTC)

Thanks, I'll try that. How can I verify whether the Xerox machin supports WIA? And will I need to install the TWAIN scan driver, or does WIA replace that functionality? Astronaut (talk) 08:52, 4 September 2010 (UTC)

Not a problem. WIA is a replacement for TWAIN. TWAIN gives you more control over the scanner, but always requires the installation of software from the manufacturer to function. TWAIN is also more tempermental. So, I always use WIA, simply because it's easier to set up. By the way, if the generic Xerox driver mentioned above doesn't work, click the "Have disk" button instead of "Next" and then point it to drivers on any disks that came with the scanner.--Best Dog Ever (talk) 09:04, 4 September 2010 (UTC)

I also work for a charity with a Xerox scanner/printer :-). In the case of our printer, the scanner does not work unless you pay a Xerox agent to enable it. At that point it will scan to a network - usually to a drive on the server. --Phil Holmes (talk) 11:19, 4 September 2010 (UTC)

Check the documentation at http://www.office.xerox.com/support/dctips/dctips.html. Looks like you need to run [[Internet Information Services|IIS]. ---— Gadget850 (Ed) ^talk 11:35, 4 September 2010 (UTC)

Extracting a date from a serial number in MS Excel

The number is in the form YYMMDDXXXXXXX. How do I extract the first 6 digits and reformat into an actual date? Roger (talk) 18:08, 4 September 2010 (UTC)

You can use LEFT(...,6) to extract the first six characters from an input string. You can similarly use MID(...) to extract any substring. Use these to extract the 2-character year, month, and date; and then feed them into one of the date and time functions to produce a date in the form of your choice (as a numeric value, or as a formatted string, or as a DATE object, and so on.

=CONCATENATE(MID($A$1, 3,2), "/", MID($A$1, 5,2), "/" MID($A$1, 1,2)) 

... might do the trick for you (where $A$1 is the source cell). Nimur (talk) 18:35, 4 September 2010 (UTC)

Perfect solution! Thanks. Roger (talk) 19:15, 4 September 2010 (UTC)

Just wanted to add a thanks from my side, I was thinking about this exact problem just earlier this week. I needed to extract dates of birth from I.D. numbers in our membership database. Thanks! Zunaid 08:31, 5 September 2010 (UTC)

This assumes the US-style mm/dd/yy format for the date and could go horribly wrong if the user's regional settings have dd/mm/yy. A more culture-independent version is =DATE(LEFT(A1,2)+2000, MID(A1,3,2), MID(A1,5,2)). If the date could be earlier than 2000 then the first parameter should be something like LEFT(A1,2)+ IF(VALUE(LEFT(A1,2))>50,1900,2000). AndrewWTaylor (talk) 11:01, 5 September 2010 (UTC)

September 5

Disk Defragmenter leaves lots of fragments.

I have just loaded and used 'Defraggler' from Piriform and it appears to leave literally hundreds of fragments and many fragmented files. But it gives no explanation. I then downloaded a trial copy of PerfectDisk 2000 which had great reviews. When I used that it also left loads of fragments and fragmented files but it labelled them as "excluded" as though it was not going to include them in the defrag process. Any ideas what is happening here please? Gurumaister (talk) 15:58, 5 September 2010 (UTC)

Some system files can't be moved and therefore can't be defragmented. I believe the same goes for any files which are in use be other programs. 82.44.55.25 (talk) 16:19, 5 September 2010 (UTC)

Thank you. doesn't that mean though that they also can't get fragmented in the first place? And could it account for over a hundred files and about three hundred counted fragments? Gurumaister (talk) 16:49, 5 September 2010 (UTC)

It's probably talking about the page file. What does the Windows defragmenter tell you when you click "Analyze" and then "View report"? (You can get to it by going to Start --> All Programs --> Accessories --> System Tools). I'm interested in (1) total fragmentation, (2) file fragmentation, and (3) pagefile fragmentation. Also, what is the free space percentage? The most important statistic in answering your question is the pagefile fragmentation. You can try using a program like PageDefrag, but that will only work if you have enough free space.--Best Dog Ever (talk) 20:28, 5 September 2010 (UTC)

One possible reason for the excluded files is Windows' boot-time optimization. Recent versions of Windows will arrange the clusters of some system files sequentially on the disk in the order they're needed during boot, which fragments those files but actually improves performance. Defragmenting them would be a bad idea. Also, a typical hard drive sequential read speed is ~50MB/sec and a typical seek time is 0.01 sec, so if a file's average fragment size is substantially larger than ~0.5 MB (a 1 GB file in 100 fragments, for example) then it's hardly worth defragmenting it (with the exception of the page file). There's also little point defragmenting files that you hardly ever read, or that are read slowly (e.g. an MP3 or AVI file). I don't know whether the major defragmentation tools implement these kinds of heuristics, though. -- BenRG (talk) 20:53, 5 September 2010 (UTC)

Why don't you use the Windows defragger Quadrupedaldiprotodont (talk) 14:01, 6 September 2010 (UTC)

In my experience if you run the defragmenter again it does reduce the fragmentation further. 92.15.11.248 (talk) 15:23, 6 September 2010 (UTC)

Excel Programming

I have been instructed, as part of an assignment, to enter this code:

Private Sub Workbook_Open()
RetVal = Shell("C:\Program Files\Windows Media Player\mplayer2.exe C:\My Music\Electricity.mp3")
End Sub

into something called "VBA editor". What is this editor, and how would I go about entering this code? —Preceding unsigned comment added by T.M.M. Dowd (talk • contribs) 17:39, 5 September 2010 (UTC)

I reformatted your source code above for readability. VBA is "Visual Basic for Applications". In Excel 2003 and earlier, you can access the VBA editor from the menu Tools > Macro > Visual Basic Editor. In Excel 2007 and later, you can access it through the "Visual Basic" item under the "Developer" tab on the ribbon. Alt-F11 is a shortcut in both versions. Once in, you will need to create a new module (menu Insert > Module) into which you can paste the above code. You can then execute the code by clicking on the run icon (green arrow) or pressing F5. If you get a "file not found" error, it is likely that one of the files is located in a different directory that is listed in your source code. You will need to locate then and update your source. -- Tom N (tcncv) talk/contrib 18:27, 5 September 2010 (UTC)

Thank you very much for your help! It didn't actually work but I think it was almost there. My problem is, I am trying to get background music in excel 2003, which I have been trying to do for the best part of a month with no avail. --T.M.M. Dowd (talk) 18:40, 5 September 2010 (UTC)

date

I have around 3,000 files who's creation and modified dates are 2064 because that's what the system date was set to on my old computer. They're should be dated 2003. The month and day are correct however. How can I convert them all to the right date? 82.44.55.25 (talk) 17:58, 5 September 2010 (UTC)

If you're running any kind of Unix, the "touch" command does what you want. If you're not, tell us what you're running. Marnanel (talk) 18:00, 5 September 2010 (UTC)

Windows 7 82.44.55.25 (talk) 19:11, 5 September 2010 (UTC)

We also need to know the file system. By default, Windows 7 will use NTFS, so you can modify the create- and modified- times. You can use the xcopy program (part of modern Windows) to copy file contents without copying file create-dates, for NTFS file systems. But if you're using some other file system, this may be impossible. Nimur (talk) 20:21, 5 September 2010 (UTC)

Yes, it's NTFS. 82.44.55.25 (talk) 20:37, 5 September 2010 (UTC)

It makes no difference whether it's NTFS or FAT, since they have the same three date stamps and they are modifiable in the same way. -- BenRG (talk) 22:15, 5 September 2010 (UTC)

Besides FAT32 and NTFS, many other file systems exist for Windows - like NFS or OpenAFS - and these definitely manage timestamps differently. Nimur (talk) 07:33, 6 September 2010 (UTC)

There are many versions of touch for Windows, but none that I've found support the --forward option that you'd need to change the year without also changing the rest of the time. Even with --forward you'd have to use different offsets for dates before and after February 29 because 2064 is a leap year while 2003 isn't. (Are you sure all of the dates are correct, incidentally?) Also, most ports of Unix touch don't let you set the creation time, and I imagine many of them will fail (in unpredictable ways) when faced with years after 2038. On the other hand, you could do this pretty easily with any half-decent programming language. Windows PowerShell is one possibility, but I haven't learned it yet. -- BenRG (talk) 22:15, 5 September 2010 (UTC)

Divx wrapped in AVI container

Supposedly my new phone can play divx videos "wrapped in AVI container." The video I want to play has .divx extension. Do I just need to change the extension to .AVI and that "wraps it in an AVI container?" Or is there more to it than that? The Hero of This Nation (talk) 20:25, 5 September 2010 (UTC)

Changing the extension to .avi won't change the Container format (digital). However, .divx files (DivX Media Format) are backwards compatible with .avi, and should play on your device. If the .divx file contains chapters or subtitles those won't work, but the main video and audio should. 82.44.55.25 (talk) 20:33, 5 September 2010 (UTC)

September 6

Is it safe to use an open wireless router (say, in a cafe)?

This document suggests to me that it's unsafe, but I just watched a Q&A session where professor Eben Moglen says that's biased by misinformation (12m14s through 13m) and an audience member agrees (13m42s through 14m).

Our wireless security article is too technical for me. Thanks. 160.39.220.66 (talk) 03:10, 6 September 2010 (UTC)

Usually, yes. But it depends on how secure your computer is and how they configured the router. If you have a firewall turned on, then you're safe from most attacks. Also, most connections to sensitive sites (e.g., online-banking sites) are encrypted by the browser (denoted by an https instead of an http in the address). So, even though people can evesdrop on your browsing sessions (since it's an open router), they can't decode information sent to sensitive sites, since that information is usually encrypted.--Best Dog Ever (talk) 03:44, 6 September 2010 (UTC)

How awesome! How surprising!! I'm already sitting on the wikilink that will point to this question when it gets archived in a few days, so I can share it with my friends and family. 160.39.220.66 (talk) 04:32, 6 September 2010 (UTC)

However you should consider always running in incognito mode and not logging in / using any accounts important to you on unencrypted connections, or your session may get captured or at worst your password gets sent unecrypted. --85.76.85.210 (talk) 11:57, 6 September 2010 (UTC)

Note that downloading email to an email client pretty much sends your password in the clear, so wireless snoopers and/or the cafe owner would be able to read this information.--86.148.22.79 (talk) 14:07, 6 September 2010 (UTC)

The above statement is true only if the client and server do not use a secure connection. Most email clients like Outlook and Thunderbird support TLS (an encrypted connection), and many web-based systems also support secure communication (usually with HTTPS). A "properly" configured email server should actually forbid you from connecting to it in an unencrypted way, forcing you to set up and use secure communications. The user should find out whether they are connecting to their email system over an encrypted channel - they can typically find information by checking the "help" section of the email system they use. Nimur (talk) 18:40, 6 September 2010 (UTC)

My statement is true with the default connection with most ISPs. I therefore thought it wise to warn the OP, whilst being aware of everything you've added.--86.148.22.79 (talk) 10:59, 7 September 2010 (UTC)

And note how easy it is not to notice Wikipedia has logged you out. --Phil Holmes (talk) 11:00, 7 September 2010 (UTC)

Note that if you are seriously concerned about security, using a secure VPN network pretty much makes the place you connect through not an issue, as it adds a seamless layer of encryption over everything you transmit and receive. --Mr.98 (talk) 00:50, 7 September 2010 (UTC)

You just have to assume that it's no different than shouting through the room. Only it's unlikely, but possible, someone is listening. As others have said, if it's a "secure" site using SSL then you're probably safe. If the connection's unencrypted, then it's possible for others to read it. The risk isn't especially that they'd access your computer, but that they'd intercept your data. Wireless encryption doesn't provide any advantage in terms of protecting the computer against a virus or something else. But the transmission from your computer, through the air, to the wireless, is at issue. Shadowjams (talk) 06:09, 7 September 2010 (UTC)

Removing IE from XP

I have a friend that has a XP Computer running Media Centre Edition. However, for some reason, he says that after his dad went to visit some sites, IE would suddenly popup at ramdom intervals. He says he di a full system scan and came up with nothing and now says he just want's to remove IE. Is this possible? Sir Stupidity (talk) 07:49, 6 September 2010 (UTC)

We have an article on everything: Removal of Internet Explorer. It is basically not easy, but doable, and might constitute infringement of copyright and/or voiding of warranty, if you care about these things. There are also other caveats, such as that the system might be less stable and certain components (I refuse to use the f word here) might not function the way they are supposed to. The article covers this all. --Ouro (blah blah) 09:34, 6 September 2010 (UTC)

Just set Firefox to the default browser Quadrupedaldiprotodont (talk) 13:59, 6 September 2010 (UTC)

That's wouldn't at all fix the problem he's discussing. --Mr.98 (talk) 14:11, 6 September 2010 (UTC)

What did he do a "full system scan" with? Can I just recommend that he do a spyware specific scan with a fully updated Spybot Search & Destroy? Because removing IE is really probably not going to fix everything, because there is clearly some malware on there causing the problem in the first place. --Mr.98 (talk) 14:13, 6 September 2010 (UTC)

Just to echo some of the others, the problem may not be IE. You should probably see exactly what is popping up on the screen. I'd bet dollars to donuts it's spyware, or he's somehow set IE to be the default program for one of his file types. — The Hand That Feeds You:^Bite 16:21, 6 September 2010 (UTC)

He used Norton Antivirus 09 to scan it, and he says it was fully updated.Sir Stupidity (talk) 03:10, 7 September 2010 (UTC)

Best and Quickest Way to a Blog

What is the best and coolest way to start a blog ? Wordpress and Blogspot seem to be unnecessarily complex. There must be a better way to put, change, add, delete, edit and fix a post in most quick manner. Also adding pics should be easy and friendly. And a newcomer should be able to comment without undergoing a discouraging ceremony like logging in, so dear to Blogspot.  Jon Ascton  (talk) 10:03, 6 September 2010 (UTC)

Try Tumblr if you want something arranged around ease of use. --Mr.98 (talk) 12:16, 6 September 2010 (UTC)

You can download Wordpress and host it yourself, then you control everything. Quadrupedaldiprotodont (talk) 13:58, 6 September 2010 (UTC)

He doesn't want to control everything. He wants it to be simple. Hosting everything and rewriting the software itself is not the simple solution. --Mr.98 (talk) 14:11, 6 September 2010 (UTC)

"Simple" depends entirely on user skill-level and what kind of web presence they already have; but since we know this OP from his prior questions on the desk, we can probably assume that he wants a free, third-party, hosted blog - probably with a browser-based "WYSIWYG"-style editor). You can try our list of social networking websites and pick the service that offers the features you need. Nowadays, it is common to offer many additional complex features in addition to the ability to post "updates." Because "blog" is such a vague and poorly-defined term, there is a huge spectrum to choose from. For example, I used to host my "blog" in the literal sense ("web log"), publishing all the transactions that my server had handled over the past day. It was very long and boring and technical, and very few people read it, even though it auto-updated it daily... but I contend that it was the "best" and "coolest" way to blog. It was extraordinarily simple to set up; I just added a cron job to run every midnight:

1 0 * * * cp /var/log/httpd/access_log /var/www/log/

It's hard to get a simpler web-`blog than that! Anyway, facetious joking aside, I really think it is easier to run your own server than to try to learn the intricacies of the latest pseudo-free web-host. The necessary skillset to operate a web-server is small and there are lots of free tutorials available. Once you have your server set up, updating a "blog" is as trivial as saving a file. In any case, we shouldn't discourage the OP from self-hosting on the grounds of "it's too difficult" - that's simply not true. Anyone can learn to self-host their website. It takes time and effort to learn the user-interface and configuration details of, say, Facebook; instead you could learn the configuration-details of your web-server - and presto - you have complete creative control of your website. Both methods have a learning curve, but only one signs over your soul to a corporation with insidious motives. Nimur (talk) 18:57, 6 September 2010 (UTC)

Are you looking for a different host, or simply editing software such as Windows Live Writer? Smallman12q (talk) 15:30, 6 September 2010 (UTC)

Well, you can start a blog just by updating an HTML page every day. But if you mean "ease of use," I'd say either [5] or [6] are your simplest ways. They won't appear to be very professional, though, as people tend not to take blogs seriously unless they're on their own hostname and not using a generic template. (Edit) Well, there's a downside to not requiring a login: spambots love it when they don't have to register a username to comment. — The Hand That Feeds You:^Bite 16:23, 6 September 2010 (UTC)

I've always found Wordpress to be pretty straight-forward to use: it gives you a lot of access to innards and customization, but you can simply ignore a lot of it. If you want a guide to getting started, Wordpress has one, in addition to extensive documentation: [7]. Commenting is open, if you'd like it to be -- there's a setting for that. One of the nicest things about Wordpress (and a lot of blogging software) is that the post-writing environment resembles programs people are already familiar with, like MS Word. Adding an image is a pretty intuitive process -- click an image icon, and then you get a dialog to browse to the image on your computer, or point it to a URL. Going with Wordpress (or Blogspot, for that matter) will ensure that you have *a lot* of documentation on anything you want to learn how to do, from the simplest to the most complex. Rishi.bedi (talk) 19:00, 6 September 2010 (UTC)

Again, I think you all have mistaken "simple" for "best" or something like that. He gives a pretty good outline of what he means by simple — he wants very few options, he wants speed of editing and adding to be a priority, he doesn't want to waste time tweaking settings. He doesn't want "power" in the sense of being able to do 10 million things with it and recoding it from the ground up. I think given his inclinations Tumblr is probably his best bet; it's arranged around Twitter-like simplicity, out of the box, no modifications needed. He doesn't need to learn how to host things or edit code or read documentation. --Mr.98 (talk) 22:23, 6 September 2010 (UTC)

Concur with Nimur in general. I am planning to set up my own server at home soon, just need to get around to it. --Ouro (blah blah) 06:08, 7 September 2010 (UTC)

Nobody doubts that setting up one's own server is a great thing if you're interested in power and flexibility. But it's not a "simple" approach. Y'all got to work on thinking outside of your own priorities! --Mr.98 (talk) 11:19, 7 September 2010 (UTC)

Reimaging HD

My friends laptop wouldn't boot and they left it in to get repaired the people fixing it said that they would reimage the HD, but haven't told him what caused the failure, not sure if the know themselves, if it was a hardware failure and not a software failure would this actually fix the problem and would his best option be to purchase a new HD as all his data is gone in any way due to the reimaging? Mo ainm~Talk 16:29, 6 September 2010 (UTC)

If your friend's hard drive physically failed, re-imaging it won't help. What exactly do you mean by "wouldn't boot" --- did you get a specific error message, or did nothing happen at all when you powered up? If it's a software failure, re-installing the OS will fix it -- the hard drive will be formatted (meaning it will have no data on it), then the OS will be installed, restoring your machine to factory settings. If this doesn't work, you definitely have a hardware failure -- but it may not necessarily be the hard drive that failed... any of the other components that are critical to start-up could be the culprit. Rishi.bedi (talk) 19:04, 6 September 2010 (UTC)

Not to sure of the specifics it was more a general question, from what he said it just wouldn't turn on when he tried, left it into get repaired and see if any data could be recovered but the only option he was given was to reimage the HD without explanation what caused it. Not being a techy he just went along with what they said. Mo ainm~Talk 19:31, 6 September 2010 (UTC)

I agree that it's rare to have a hard-drive equipment failure that completely screws up your system, but can be fixed with a re-imaging. (At least with equipment made in the last decade and half. HD's were more touchy in the Olden Days.)

If I were your friend, I would insist on learning exactly what went wrong. "re-imaging" the harddrive is often something that incompetent computer repairmen do when they don't know how to fix your problem. It's a throw-the-baby-out-with-the-bathwater solution that will 'fix' any software or operating system problem.

(All that said, personally, when I have doubts about a hard-drive, even irrational doubts, I replace it immediately. HD's aren't that expensive anymore. It's worth it to me for the peace of mind.) APL (talk) 19:41, 6 September 2010 (UTC)

The shop can run disk diagnostics to give an indication whether there is (at the time those are run) a hardware problem that they can detect. If there is not, they are liable to assume it was a software problem; at that point, re-imaging the hard drive is, from their standpoint, a reasonable solution.

I don't think such technicians in general have the tools or the knowledge to figure out "what went wrong", mostly because it isn't economically feasible. There are a huge number of possibilities, and there is no guarantee that a world-class expert with all the tools he or she could wish for would be able to figure it out in a reasonable time. Repair shops aren't usually set up for that sort of thing, because customers are not usually prepared to pay for it.

Just picture it: "It is difficult or impossible to tell what went wrong; if you want to leave it here and have us study it, then tell us a maximum number of hours to spend and we'll do our best." Not only will people not pay for that, they will be put off by the suggestion.

I do agree that, if you're going to lose the data anyway, a new hard drive should definitely be considered.

rc (talk) 20:04, 6 September 2010 (UTC)

Accept big, output small

What do you call the networking principle that says you should accept the widest range of values possible but output a very narrowly defined set? --STUART (talk) 18:00, 6 September 2010 (UTC)

You're probably thinking of Postel's Law, see Robustness principle. -- 78.43.71.155 (talk) 18:47, 6 September 2010 (UTC)

Oldest and Newest YouTube video, please?

What are the oldest and newest YouTube videos? Thanks, --70.179.165.170 (talk) 19:32, 6 September 2010 (UTC)

The first can be found by typing first youtube video into google; it so happens that the Wikipedia article on YouTube mentions it (search for the above-mentioned phrase). As to the newest, that keeps changing all the time, as people upload new videos. 88.112.56.9 (talk) 19:50, 6 September 2010 (UTC)

Well then, about the newest: What is the newest video as of the time you submit your reply? --70.179.165.170 (talk) 20:41, 6 September 2010 (UTC)

That will be a different answer by the time you read it. [8] claims to have "today's 101 top rated videos from YouTube™, updated daily". Dbfirs 00:39, 7 September 2010 (UTC)

In fact it's probably a fairly meaningless question since the answer is likely to be different even by the time you've finished receiving the page which tells you which is the newest video (presuming Youtube has some sort of live feed of new videos). [9] notes that 24 videos are uploaded every minute although doesn't specify when that was. This must be an average and clearly there would be less at some times particularly when those in the US and to a less extent Western Europe are sleeping or not active but even so, it's not difficult to imagine it's rare that there isn't a new video every 15 seconds at a minimum. In other words, even saying "The newest video is 'Why I love chicks and kiwis' uploaded by Duck Cheney today at 20:52:23 NZST" is a statement that even if you do get the info from Youtube quickly enough probably won't be true by the time you say it out loud. Nil Einne (talk) 08:51, 7 September 2010 (UTC)

Secondary question: What are the most up-to-date stats on YouTube?

For example, how many videos exist on there so far, how many users, and, on average, how many videos per user? --70.179.165.170 (talk) 20:39, 6 September 2010 (UTC)

You could try to search the web for this information. It is somewhat unlikely that someone here has up to date figures on these things in his head; so we are reduced to your web search slave service. Google for something like number of videos on youtube. 88.112.56.9 (talk) 21:58, 6 September 2010 (UTC)

Youtube

How are youtube video urls generated? With this logic (talk) 20:48, 6 September 2010 (UTC)

They appear to be just unique IDs. They don't have any relation to the content of the video. An easy scheme would just to run a hash function on a very large random number (or the product of two large random numbers), check to see if that ID is already used (pretty unlikely), if so, repeat, if not, use it. Their scheme seems to be an 11-digit ID that is case sensitive, can include numbers and dashes, which is a huge possible set of IDs. --Mr.98 (talk) 23:41, 6 September 2010 (UTC)

(Specifically, a YouTube video ID is made of 10 characters from A-Z, a-z, 0-9, - and _, plus one character from AEIMQUYcgkosw048 for a total of 2⁶⁴ or about 18 × 10¹⁸ possible IDs.) --Bavi H (talk) 03:12, 7 September 2010 (UTC)

Running a hash function on a long random number does not give any more randomness that using a short (i.e., 64-bit in this case) random number directly, and the latter is obviously more efficient.—Emil J. 14:05, 7 September 2010 (UTC)

September 7

Second Internet Line Cable

Hi, I help manage the wired and WiFi internet access for a Bed & breakfast-sized apartment of around 30 people. Currently, I have one TV cable plugged into a modem, which is then plugged into a series of routers that help cover the entire house. Frequently, when all residents are using the internet at once, the connection is unstable and will randomly drop users off the Wifi access.

I am thinking of connecting a second TV cable into a second modem and plugging some routers into that to help spread the load.

My questions are: (1) Will I have to contact my ISP (Time Warner) and pay for the cost of an additional connection? And (2) will this indeed work?

Thanks, Acceptable (talk) 00:07, 7 September 2010 (UTC)

We need some more information. First, are you sure you have several routers, and not merely several wireless access points? And do you have any diagnosis about what actually is occurring when the network fails? (Are the users unable to obtain an IP, for example? Or are they unable to locate a wireless network?) There are some "best practice" guidelines for creating and managing a scalable wireless network (for example, here is Cisco's product lineup brochure). It is very unusual to have "several" routers in order to service ~ 30 connections - you really only need one, and the rest of the house should be covered with WAPs. Can you describe your network topology and the failure symptoms a bit more? Nimur (talk) 01:51, 7 September 2010 (UTC)

First, are each of your routers on the same channel? Neighboring routers should be on different channels -- either 1, 6, or 11 -- to prevent interference. Also, lay out your network so wireless signals from each router overlap each other by 15-20%. Otherwise, they will compete for connections from users.

If the bottleneck is really your cable connection, then you can purchase another cable connnection and cable modem from your ISP. You will also need to purchase a router with two WAN ports, like this wireless model or this wired model. You can then plug in an ethernet cable from each cable modem into each of the two WAN ports in the router. This is called channel bonding. You can also installl a network card with three or more ethernet jacks in a desktop computer, using it as a router. Here is an example of such a card.

Another solution would be to ask your ISP for more bandwidth. Most cable connections are capped at a much lower speed than what is available. If you pay them more money, they can probably increase the speed of your connection. I also have a cable-internet connection. I pay my ISP an extra $20 per month for twice as much bandwidth (23 mbps).--Best Dog Ever (talk) 02:45, 7 September 2010 (UTC)

Recording a Skype conversation

I have a client here in Canada whose wife is still in their country of origin. He uses Skype to talk to her regularly. He wants to bring her to Canada but our wonderful officials are skeptical that he talks with her as frequently as he says he does. Is there any way to record the Skype conversations to prove that he does talk with his wife? 99.250.117.26 (talk) 02:34, 7 September 2010 (UTC)

You can always just use a microphone and record it from the speakers.Sir Stupidity (talk) 03:02, 7 September 2010 (UTC)

I've used Pamela. It's easy to use and the sound quality is excellent.--Best Dog Ever (talk) 03:04, 7 September 2010 (UTC)

Uh, careful there. Recording actual conversations might be problematic due to wiretapping laws (this is not legal advice, but rather advice to seek legal advice by a qualified professional in the field of law, should you really want to record the conversation). Consider the situation that your client some day decides to break up with his wife, and she suddenly "doesn't remember" agreeing to the recordings. If your legislation requires two-party consent to recordings, and there's no proof that she agreed, she might drag him to court.

Therefore, I would suggest that you investigate if there are any ways to record the connection data, similar to call detail records on a regular phone line. That way, the actual conversation stays private. -- 78.43.71.155 (talk) 08:31, 7 September 2010 (UTC)

Would a recording actually help? Surely officials want a log of calls made. However, I doubt a log of Skype calls would do because they might claim he could tamper with the evidence in his favour. I suggest your client uses a regular land line for a while so he can build up an independant log of call activity at the phone company, a log which the officials can then obtain through a legal request to the phone company. Astronaut (talk) 12:05, 7 September 2010 (UTC)

Way better than recording the speakers with a microphone, just record your stero output direct from the sound card. Also, to the pseudo-lawyers ranting about recording calls being wiretapping, it ain't illegal if you say you're recording the call, then the other person can hang up if they don't want to be recorded. This happens all the time with call centers that say "this call might be monitored for training purposes" etc etc. Quadrupedaldiprotodont (talk) 14:02, 7 September 2010 (UTC)

Viruses

How do you tell if a program has a virus? --The High Fin Sperm Whale 03:59, 7 September 2010 (UTC)

Simple answer: someone else has identified it as a virus and a search of your computer reveals that common feature. Real answer: You have to define "virus" first, and then realize that any program that does something you don't want without you knowing it is a "virus" for all practical purposes. Is there a more practical application you're interested in? Shadowjams (talk) 06:11, 7 September 2010 (UTC)

(ec) Well, if files for an application are indeed infected (i. e. code is attached to files) then there are three possibilities. The original application will either not run at all (i. e. if the malicious code is appended to the main executable clumsily), it will hang or crash or break in the middle of an operation (if the virus code is appended to a different file which is not run at startup, or if the code only corrupted a portion of the file), or it will run as normal (because the malicious code is appended in such a way that it does not interrupt the operation of the original file). In most cases it will be the first, rarely the second, the third may take place also. Is this going in the direction you were thinking? Note that by now many 'viruses' (malware, etc.) are so large and intricate that they will be (sets of) standalone files rather than a kilobyte or two in size attaching itself to a file. Back in the day, viruses were small, small, small, with the most prevalent not exceeding a few kilobytes, and many l'art pour l'art viruses were under 100 bytes in length! Hope this helps. --Ouro (blah blah) 06:17, 7 September 2010 (UTC)

It depends on the type of virus. A virus as described above will add to the size of a file, sometimes a few hundred bytes, sometimes many thousands of bytes. There is also strange behavoir: programs crashing, things that used to work just not working any more (for example: a virus might disable access to the task manager), a flurry of unwanted results in an internet search, messages popping up, and so on. A macro virus will make your office document bigger.

However, all the recent virus/malware I've seen has come in separate programs that are started when the computer starts, either as a service or as a startup program configured in the registry like a regular program. Some malware makers think they are providing you with a genuine product (and market it such to their customers who pay them to place their ads on x thousand PCs), which creates an entry in the list of installed programs - just one you didn't want or know was being installed. You may nothing about it until a friend mentions that they got some spam or a virus in an email from you.

In all, it is a good idea to familiarise yourself with the normal operation of your computer, what programs and services start, the kind of noises (fan and disk) that it makes, and how it performs under various conditions. That makes it easier to spot times when it seems to be misbehaving or taking much longer to do something. Astronaut (talk) 11:57, 7 September 2010 (UTC)

Run a virus scanner Quadrupedaldiprotodont (talk) 13:59, 7 September 2010 (UTC)

I was more thinking of how to figure it out before you install a program. I want to install hugin.exe, but I want to know it's safe. Is there any way to tell without putting my computer at risk? --The High Fin Sperm Whale 16:31, 7 September 2010 (UTC)

From looking at the site and the fact that it has a Wikipedia article with no mention of malicious dangers, I'd say it is pretty safe. And most antivirus software will detect viruses (if there are any) during or even before an install, and take measures to ensure the safety of your computer. But if you're really worried, you could install the program inside a virtual machine such as VirtualBox, Windows Virtual PC or QEMU. So that if it did turn out to be a virus, only the virtual machine would be affected and you could simply close and delete it with no danger to your actual OS. 1230049-0012394-C (talk) 17:58, 7 September 2010 (UTC)

Assuming the virtual machine is configured correctly, of course. If it has internet connectivity, malware can still contact its botnet and start spamming. And if the VM has remembered network connections to its host that give it write access there.... Unilynx (talk) 18:09, 7 September 2010 (UTC)

Batch file question - how to find the newest document in a subdirectory structure

How can I find out which PDF file in a subdirectory structure full of PDFs is the newest file? dir *.pdf /s /b delivers a list of all pdfs in the subdirectory structure with full paths (which is what I want), but doesn't sort them by date. dir *.pdf /b /o-d does sort by date, but doesn't descend into subdirectories. Combining these two into dir *.pdf /s /b /o-d doesn't deliver the expected result - it sorts by date, but per directory, while I'm looking for the *one* newest file of all directories. To sum it up, what I have is:

c:\mypdfs\bar\new.pdf
c:\mypdfs\bar\newer.pdf
c:\mypdfs\foo\old.pdf
c:\mypdfs\foo\older.pdf
c:\mypdfs\ney\newest.pdf
c:\mypdfs\ney\oldest.pdf

What I want is

c:\mypdfs\ney\newest.pdf
c:\mypdfs\bar\newer.pdf
c:\mypdfs\bar\new.pdf
c:\mypdfs\foo\old.pdf
c:\mypdfs\foo\older.pdf
c:\mypdfs\ney\oldest.pdf

(actually I only need c:\mypdfs\ney\newest.pdf, I don't care if the rest shows up or not)

What dir *.pdf /s /b /o-d delivers is

c:\mypdfs\bar\newer.pdf
c:\mypdfs\bar\new.pdf
c:\mypdfs\foo\old.pdf
c:\mypdfs\foo\older.pdf
c:\mypdfs\ney\newest.pdf
c:\mypdfs\ney\oldest.pdf

The code only needs to run on W2K or newer, so in addition to the builtin batch cmds, the usual standard tools of these Windows versions are available. Any ideas? -- 78.43.71.155 (talk) 08:22, 7 September 2010 (UTC)

Use Windows explorer, search for *.pdf, sort by date modified? --86.148.22.79 (talk) 09:07, 7 September 2010 (UTC)

Windows explorer isn't exactly a batch file solution, or is it? ;-) -- 78.43.71.155 (talk) 10:22, 7 September 2010 (UTC)

Good point. I read the question but not the header. --Phil Holmes (talk) 11:01, 7 September 2010 (UTC)

This is not a complete solution, and is just a command line, not a batch file, but might be a start --

dir *.pdf | find /v "Directory of" | find /I "pdf" | sort /R

That will get you a full list sorted by date. In this case, the first line of the output is the newest file, with date and size information. Extracting just the file name from that single line is left as an exercise for the reader ;-) --LarryMac | Talk 12:55, 7 September 2010 (UTC)

Nope, that's not really helpful, either - as it doesn't descend into subdirectories. Sorting by date within a single directory is not a problem, that's what dir /o-d is for (the "-" doing what you achieved with "sort /r"). Also, matching for "Directory of" means it's not language-independent. -- 78.43.71.155 (talk) 13:17, 7 September 2010 (UTC)

I left off the /s on the dir command, but I assure you the proof of concept works; you might have at least given that a try. Language independence was not listed as a requirement, so if you're going to reject honest efforts to assist and change the requirements, then I'll stop right here. --LarryMac | Talk 13:23, 7 September 2010 (UTC)

Sorry to burst your bubble there, but I did try it, including the /s, before posting my comment, and it does not sort the way you claim. The newest pdf shows up at the fifth position from below. Thinking about it, this also has to do with the language issue - dates are in DD.MM.YYYY format here (and even if we were using MM/DD/YYYY, it probably gets messy once we have files from different years - a YYYY-MM-DD style display would help, but Windows doesn't offer that). Also, your solution doesn't provide the file including its full path (which is what I need and why I was using the example above). -- 78.43.71.155 (talk) 14:06, 7 September 2010 (UTC)

Google translate default/detect language

I sometimes use Google translate but I find it annoying that it always defaults to Spanish -> English translation. Is there a way I can get it ti detect the input language automatically, or keep the last language used, perhaps in a cookie? And why does it default to Spanish anyway, it's not like it's the first in the list? Astronaut (talk) 11:31, 7 September 2010 (UTC)

Spanish is a popular language. And there is an auto detect feature, and it is set to default from my computer.Sir Stupidity (talk) 11:56, 7 September 2010 (UTC)

(e/c) It's more clever than it looks. If you frequently request translations from another language, your default will indeed eventually switch to that language, and a couple more languages may be moved to the top of the drop-down menu. I assume that it defaults to default to Spanish because it is the most frequently requested language on English-language Google.—Emil J. 12:00, 7 September 2010 (UTC)

(That is, unless you keep changing your IP and deleting your cookies to prevent Google from keeping track of you.—Emil J. 12:09, 7 September 2010 (UTC))

It sometimes retains/detcts the language if I use IE 8's Google translate accelerator, but otherwise the cookie is not working for me. Astronaut (talk) 13:30, 7 September 2010 (UTC)

Google

If google for some reason decided they wanted to shut down all of their services tomorrow (email, search, maps, etc)

1. Would they legally be allowed to?
2. What would be the impact on society? —Preceding unsigned comment added by Half charged (talk • contribs) 13:45, 7 September 2010 (UTC)

I really don't see anything that would legally prevent Google from shutting down all their services. They're still a privately-owned company, right? JIP | Talk 13:55, 7 September 2010 (UTC)

Google is now a publicly traded company (see History of Google#Financing and initial public offering), which means that they'd have to deal with shareholders if they wanted to liquidate. However, it also says that "The vast majority of Google's 271 million shares remained under Google's control", which presumably means that they could force a liquidation if push came to shove. Buddy431 (talk) 14:29, 7 September 2010 (UTC)

To explain Buddy431's comment about having to "deal with shareholders": The directors and, generally, the managers of any company (with more than one shareholder) have a fiduciary duty to maximize shareholder value. If the managers of Google were to shut down all their services tomorrow, and if the board of directors didn't immediately fire all the managers, install new ones, and get them to restart the services, many shareholders would immediately file a class-action lawsuit in order to kick out the directors and managers and get them to restart the services. This would take a while, of course. To directly answer the first question, it would not be illegal for Google to shut down all their services; no laws would be broken, unless maybe Google has entered into agreements with governments, and those governments have laws that forbid a shutdown. But a shutdown would not last long anyway, because of the fiduciary duty lawsuits — unless the directors and managers could show that it was in the best interest of the shareholders to shut down the services. If they could show that (and I do not think this is remotely possible), then, yes, they would even be immune to any fiduciary duty lawsuit. Comet Tuttle (talk) 16:57, 7 September 2010 (UTC)

Remember as well Google isn't simply a company providing free stuff as some people still think, but a massive company which deals with a large variety of people and companies on a commercial level with contracts and the like. These likely create responsibilities which would cause problems for them if they try to just 'shut down' their services. For example, they have a search deal with Yahoo in Japan and others use their search too, Youtube has a variety of deals with media companies, I'm pretty sure some mobile phone companies and networks have deals with Google for search, maps and of course the open source Android, many companies pay for Google Apps (and while it's not something I've looked in to I suspect the even the free edu variant does involve some sort of contract which Google can't just terminate willy-nilly), there are likely a variety of other support contracts and the like involved etc. And let's not forget the master of them all, Google's advertising business (i.e. all the advertisers). Of course there would likely be a variety of more direct creditors like banks and suppliers who won't be too happy either... Nil Einne (talk) 17:44, 7 September 2010 (UTC)

Did you guys forget about Google Analytics?Smallman12q (talk) 22:19, 7 September 2010 (UTC)

I don't see how Google Analytics changes anything. When you sign up for Google Analytics, Google doesn't tell you, "We warrant that Google Analytics will be available for you to use in perpetuity." Comet Tuttle (talk) 23:29, 7 September 2010 (UTC)

The section Service Levels in their TOS states that:

Google does not guarantee the Service will be operable at all times or during any down time (1) caused by outages to any public Internet backbones, networks or servers, (2) caused by any failures of Your equipment, systems or local access services, (3) for previously scheduled maintenance or (4) relating to events beyond Google's (or its wholly owned subsidiaries') control such as strikes, riots, insurrection, fires, floods, explosions, war, governmental action, labor conditions, earthquakes, natural disasters, or interruptions in Internet services to an area where Google (or its wholly owned subsidiaries) or Your servers are located or co-located.

Shutting down their services is not beyond their control. (On a side note, its interesting to see they account for riots, and insurrection).Smallman12q (talk) 00:10, 8 September 2010 (UTC)

Web

Explain this http://cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.cache.click.down2crazy.com/ 86.72.16.66 (talk) 16:30, 7 September 2010 (UTC)

See subdomain. Comet Tuttle (talk) 17:00, 7 September 2010 (UTC)

Frustrating ADSL problem

This has been bugging me for 4 months and I've tried loads of different ways to fix the problem with no avail. Problem is that my ADSL modem keeps disconnectiong (randomly and intermittently) during which the DSL light flashes, then DSL and Internet lights go off, then after some random amount of time the DSL light flashes then the modem connects to the internet again. While the DSL light is flashing, the DSL status on the modem software says 'synchronising'. DS and US line attenuation before and during the problem is typically in the low 30's and my telco guy says he only gets worried above 50. So, I've called the telco people multiple times; they checked the exchange, resynched my line from the exchange, replaced the line from the repeater to my house, and checked line noise many times. I've tried 4 different ISP's to no avail. I've also tried two brands of modems, including a swap-out of the current modem (duoPlus 300WR). I suspect something is triggering the modem to disconnect and 'synchronise the line' - any gurus out there know how to stop this trigger? Any other ideas? Sandman30s (talk) 20:17, 7 September 2010 (UTC)

help

i have ubuntu and win7 installed on my laptop. windows won't boot, and the only os boot option is GRUB. i installed ubuntu because windows gave me <missing operating system> and i know why.

so tl;dr how do i fix my MBR from ubuntu?

/and i can't use CDs —Preceding unsigned comment added by Boodalu (talk • contribs) 22:47, 7 September 2010 (UTC)

September 8

What is a GeekTool script?

Does this compound word mean anything other than "desktop theme" for a Mac computer? 76.27.175.80 (talk) 00:23, 8 September 2010 (UTC)