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April 21

how does apple keep flash from running?

does anybody know this? (i'm just curious, not interested in any hacking). does the OS recognize the flash app code and refuse to load it? or does it recognize the flash files and refuse to load them? or what? frankly, the concept of an OS that refuses to run a particular application (rather than not having the resources) is new to me. Gzuckier (talk) 03:26, 21 April 2010 (UTC)

I assume you're referring to the iPhone and the iPad since Flash does run on Apple's Mac OS X. Most of the time, the Flash Player is pre-installed on smart phones. But Apple refuses to pre-install it. The next possible way to install the Flash Player is through the iPhone App Store. But Apple won't allow it in its App Store. So, the only remaining way to obtain the Flash Player would be to jailbreak your iPhone and download it through a third-party store (like Cydia). You can't install apps on the iPhone from anywhere but the App Store unless you jailbreak your phone. But I don't know if Adobe will ever bother to release a final version of an iPhone flash player since most iPhone users won't be able to install it. Last time I heard, it was in beta.--Best Dog Ever (talk) 03:48, 21 April 2010 (UTC)

You are making a HUGE assumption that there is a flash player that will run just fine on an iphone and that the iphone OS refuses to install it. Instead, ask if there is a flash player that will run just fine on the iphone OS. When programs do not exist, nobody is refusing to install or run them. You may as well ask why your computer refuses to run Duke Nukem Forever. -- kainaw™ 04:43, 21 April 2010 (UTC)

Yes, it's a strange assumption that Flash should just work, as if by magic. If you have a brand-new Windows install, Flash isn't going to work on that, either. Your web browser will say something like "Plugin Required" and send you to download and install Adobe Flash Player. The difference is that on the iPhone, there is no Adobe Flash Player to download and install. -- Coneslayer (talk) 12:13, 21 April 2010 (UTC)

That's odd. Why won't Apple "allow it in its App Store"? Seems like a strange thing for Apple to say. Astronaut (talk) 12:54, 21 April 2010 (UTC)

Apple fiercely defends its walled garden, and Apple hates Adobe. Here's a longer discussion. -- Coneslayer (talk) 13:30, 21 April 2010 (UTC)

Apple's explanations for not having Flash on the iPhone state that it doesn't run well enough, it's a security risk, and flash is an interpreter so it wouldn't be allowed on the App Store even if the first two points aren't true. Caltsar (talk) 14:46, 21 April 2010 (UTC)

This recent asktog column says, "Jobs doesn’t like Flash. It has a slow, clumsy, weird interface, and he’s elected to "cripple" his mobile devices to rid the industry of its dependence on it." Tog goes on to compare this decision to Jobs's insistence that the original Macintosh not have arrow keys on its keyboard, temporarily "crippling" the Macintosh in order to specifically make sure that Mac software developers designed their apps around the use of the mouse, rather than directly porting their existing IBM PC apps, which relied on the arrow keys for things like menu navigation. Comet Tuttle (talk) 17:45, 21 April 2010 (UTC)

A Potential misconception here is that flash files "just work" on any computer and would need to be "blocked". They don't. They need a plug-in written for every type of computer they run on. Adobe works hard to make it seem like it "just works", but actually it depends on a getting a piece of software from Adobe that's separate from your web-browser.

It's not a matter of blocking them as much as it is never giving you the software they depend on in the first place. APL (talk) 15:10, 21 April 2010 (UTC)

Except in this case, it is deliberate blocking. Adobe would love to produce a version of Flash for the iPhone and iPad and would take the time to figure out how to make it happen, except they know Apple won't approve it, and so it would be a waste of effort. If Apple said they'd approve Flash in some form (e.g. Flash Lite), you can bet that Adobe would find a way to bundle it up. Apple has made a deliberate choice to ban Flash tech from their mobile products; it is not Adobe's fault to any particular degree. (Apple of course justifies it as a technical decision, but won't define the technical objections. If they said, "it could only use x% of the processor time", I am sure Adobe would modify it as requested. As it is, they've basically just been told, "no." Personally I find this a bit ridiculous—worse than anything Microsoft ever did—and am pretty appalled by it, even as someone who uses a MacBook as his main computer.) --Mr.98 (talk) 17:50, 21 April 2010 (UTC)

APL's point is that in order for Flash to work on any device, Adobe first has to write a version of their Flash player for that device, and it's not as simple as Apple saying "yes" and flipping a switch and then Flash works on the iPhone. Comet Tuttle (talk) 17:54, 21 April 2010 (UTC)

Right, but the issue here is not a technical one. If Apple did "flip the switch"—allow Adobe to code a Flash application for the iPhone—there would be one probably near instantly. Adobe is jumping at the bit for this. The problem is not that Adobe has not or could not write an application for the iPhone. The problem is 100% Apple not letting them publish a version for it. It is not a technical issue. It is business. --Mr.98 (talk) 18:13, 21 April 2010 (UTC)

Well, we understand that Apple is deliberately blocking Flash on the iPhone, by barring any apps that carry a Flash player; but saying "the issue here is not a technical one" is, I think, misleading to the original poster, whose question shows that he or she is under a misapprehension about how Flash has to be written specifically for each platform. I think a more complete answer would be "For Flash to run on the iPhone, Adobe has to take the technical effort to write a Flash player for the iPhone. That has happened, and the Flash player on the iPhone is ready; but Apple has made the business decision to ban any app that carries a Flash player." Comet Tuttle (talk) 18:27, 21 April 2010 (UTC)

No, I understand that flash would have to be ported to the Ipad/phone platform, but assumed that it's a matter of reworking the big pile of C or whatever, as with porting anything to anything. Hadn't occurred to me that it would have to be offered via the Apple store, etc.... so does that mean that if I were a genius, I could write a Flash interpreter via the Ipad SDK or whatever for my own use that would work? Not that I could, but hypothetically? Gzuckier (talk) 00:52, 22 April 2010 (UTC)

You wouldn't have to write one from scratch. You could just port Gnash to the iPhone using Xcode. Here's the source code for Gnash: [1].--Best Dog Ever (talk) 01:16, 22 April 2010 (UTC)

A week after the original poster asked this question, Steve Jobs wrote a letter / blog post detailing why Apple isn't allowing Flash on the iPhone or iPad. Comet Tuttle (talk) 17:15, 29 April 2010 (UTC)

Googlebot indexing

Will a subdirectory-tree on a web server, that has has permissions 777, and which is used for uploads and as a file repository for a php-based application, located on a site which itself is indexed by googlebot, also be visible to googlebot and similar web crawlers?

The application in question is MediaWiki. Short urls (without the question mark) are not used. There are no ingoing links to the directory, its name appears only in LocalSettings.php. There is no anonymous ftp, and login is required to access the wiki. I'm also assuming that the directory has a long, randomly generated name.

I've asked a question similar to this one before, read Web_Crawler#Crawling_the_Deep_Web, as well as this xkcd comic, but am still not totally sure about the answer. Thanks, --NorwegianBlue ^talk 07:43, 21 April 2010 (UTC)

Put an XML site map on the site so the crawler will know where to find stuff. That works better than relying on the link graph. 66.127.53.162 (talk) 08:17, 21 April 2010 (UTC)

Sorry for not being clear enough, the intention is that the crawler should not be able to index these files. --NorwegianBlue ^talk 10:46, 21 April 2010 (UTC)

Had you considered using a robots.txt exclusion file? --Phil Holmes (talk) 15:08, 21 April 2010 (UTC)

Oh. Yes, use either a robots.txt or comparable meta tags (see the article Phil Holmes linked to). Note that there are evil crawlers that ignore such directives. 66.127.53.162 (talk) 16:31, 21 April 2010 (UTC)

If you want to prevent a web spider from indexing it, the best option is to restrict access to that directory, either by requiring a login or by denying delivery at the server level (for example, deny all except an IP whitelist; or require a login/password; and control this with an .htaccess file). Alternately, if you have absolutely no links to that subdirectory, ("security through obscurity"), the directory's presence should be totally unknown to all spiders. Note that if you ever accidentally create a link (or if a spider somehow guesses the directory name), the "obscurity" scheme provides no measure to deny access to that robot. (I know that in MediaWiki, especially if you post files on the wiki, there will be links to that upload directory - but you stated that these wiki pages already have some access control).

Ideally, you want identical access control for the .htaccess file and the wiki login - there may be some way to do this using session-sharing and a unified login. Ultimately it boils down to how strongly you seek to protect / deny access. I strongly recommend that you use an authentication scheme - htaccess files are easy to understand and implement, and are a good way to augment a "security through obscurity" scheme. If you are particularly worried about protecting your content, consider requiring additional measures, (in order of increasing complexity/security): secure HTTP, requiring a captcha, encrypting the directory contents, or replacing the simplistic "uploads" directory with a full-blown web-application and secure network-storage scheme that enables per-user authentication. Eventually, your secure system must migrate to a non-public network if you want the maximum level of security. Nimur (talk) 17:47, 21 April 2010 (UTC)

If you're trying to run a private site then you have to use login authentication and trust your users, yes. Keep in mind that if the site has any external links at all, those can disclose the site's existence through referer headers when users click on the links. If you're just trying to keep a low profile from mass visibility (spelled Google), then robots.txt seems sufficient for most purposes. 66.127.53.162 (talk) 20:22, 21 April 2010 (UTC)

Although "robots.txt" is a perfectly valid answer to my question, it makes sense to consider not-so-friendly bots or other intruders, who might use "robots.txt" for the exact opposite of what it's intended for. This is indeed a case of "security through obscurity". So it seems .htaccess + .htpasswd is the way to go. I wasn't aware it protected all subdirectories (of which there are a lot in a MediaWiki file repository). I tried it, and my testing so far indicates that its presence doesn't confuse the MediaWiki software, files are uploaded and downloaded fine. However if I try to browse the "secret" directory, which used to be accessible to someone who knew its name, I'm now prompted for a username and password. Thanks everyone! --NorwegianBlue ^talk 16:55, 22 April 2010 (UTC)

Editing MS Word dictionary

While proof reading a document I add erroneous entries into the dictionary because I click on the wrong item in the right click menu. while I should have clicked on the right substitution I wrongly click on the add to "dictionary". How can I delete these custom entries?--117.204.83.62 (talk) 09:45, 21 April 2010 (UTC)

In Word 2003:

• open a document, ensure there's some mis-spelled text in the document
• F7 (brings up the spell checker dialogue box)
• Options
• Custom Dictionaries
• Select CUSTOMDIC and Modify
• Add to or delete items from the CUSTOMDIC --Tagishsimon (talk) 09:54, 21 April 2010 (UTC)

Thank you for the help.--117.207.146.213 (talk) 10:02, 21 April 2010 (UTC)

Win XP language and keyboard

Resolved

I changed my language on XP from US English to English UK but the UK English keyboard doesn't suit me because I get @ symbol when I press " key. So I kept the language as UK English and chose the keyboard as US English. However, when I press " nothing appears. It the symbol is to appear I have to press the space bar once. No space is added though. How can I get around this? --117.207.146.213 (talk) 10:05, 21 April 2010 (UTC)

What is the physical layout of your actual keyboard? US keyboards and UK keyboards have different layouts and in particular Shift-2 will create a '@' on a US keyboard and a '"' on a UK keyboard. However, the dead key behavoir you describe seems to be a feature of the US-International keyboard, the UK-extended keyboard layouts and other layouts too. Maybe you picked the wrong version in the XP keyboard settings or you have a different keyboard altogether. Astronaut (talk) 12:49, 21 April 2010 (UTC)

The physical layout of my keyboard is US keyboards as I guess from the image there. I have chosen the US-International keyboard along with English UK. I see that it has this dead key behaviour. Let me try US keyboards and see.

-117.204.89.229 (talk) 07:04, 22 April 2010 (UTC)

I removed US International Keyboard and added US keyboard. That fixed it. Thank you for the advice. -117.204.91.238 (talk) 12:28, 22 April 2010 (UTC)

Is there a way to determine the default gateway in JavaScript, similar to myIpAddress() for the IP?

I am trying to create a proxy autoconfiguration file (PAC), however, I am running into a Firefox bug: myIpAddress() returns an IPv6 address under Windows 7, even though the IPv6 addresses aren't used (they are Link-local only). As Firefox doesn't support myIpAddressEx() (which returns a list of all IP addresses the client has, IPv4 and IPv6 alike) like Internet Explorer does, I'm stuck here, as I need to switch proxies depending on the network the client belongs to.

However, since I don't need the IP, only the network, and only the IPv4 network has a defined gateway address, I am hoping that there is a way to find out the default gateway in JavaScript, so I could use that for my script. Any ideas? -- 78.43.60.58 (talk) 17:54, 21 April 2010 (UTC)

Addendum: I found this snippet of code that returns 127.0.0.1:

alert('Your IP address is: '+java.net.InetAddress.getLocalHost().getHostAddress());

It seems that it calls Java from within JavaScript, which makes me wonder if

• this will work from a PAC file and
• there's a command to query the other IP addresses or the default gateway instead of getLocalHost()

If Java is not affected by the IPv6 bug I'm seeing in JavaScript, this might help me.

Anyone out there that knows enough Java to change that one-liner into something that returns the non-localhost IP(s) or the default gateway? -- 78.43.60.58 (talk) 18:32, 21 April 2010 (UTC)

torrent proxy

If I use a proxy server with utorrent, and select "Use proxy server for peer-to-peer cnnections", will my real ip be compleatly hidden from others, or is there some way it could leak? —Preceding unsigned comment added by 81.198.37.158 (talk) 18:11, 21 April 2010 (UTC)

It can always leak. 66.127.53.162 (talk) 20:24, 21 April 2010 (UTC)

What happened to Yahoo mail?

I found out (probably here) that you can click on the yellow triangle twice if there is one. This is what came up and it gave me the option to copy, so I did. ---

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; WOW64; Trident/4.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729) Timestamp: Wed, 21 Apr 2010 20:47:21 UTC

Message: Exception thrown and not caught Line: 1 Char: 45847 Code: 0 URI: http://mail.yimg.com/d/combo?/mg/10_1_9/js/yui_utils.js&/mg/10_1_9/js/core.js&bc/bc_2.0.4.js&/mg/10_1_9/js/darla.js&/uh/15/js/uh_mail_rsa-1.0.3.js&/mg/10_1_9/js/async.js&/ult/ylc_1.9.js&/mg/10_1_9/js/imboot.js&/gx/t7a/js/yui_loader_mg/34541ce650d3379b3d52c78d4fe681a9_1.js&/gx/t7a/js/combo/init/us/0f36956c5c2ed4808b5a7a2be027ffad_1.js&/gx/t7a/js/combo/init/us/ycw_gx_1.js --- I usually notice the time the draft was last saved has changed when I've updated an email I am composing (I use this as a notepad), but I happened to see this one hadn't changed in two hours. I looked and there was the yellow triangle. I clicked on "Send" but still have a rotating circle beside the arrow. So I copied and pasted to a new email and it sent fine.

Here are the details of my computer, at least on the date at the end of those details.Vchimpanzee · talk · contributions · 21:12, 21 April 2010 (UTC)

By the way, what do you call that yellow triangle on Wikipedia? When I click on a link, I get Nazi concentration camp badges.Vchimpanzee · talk · contributions · 21:14, 21 April 2010 (UTC)

I just logged into my Yahoo Mail account, and I don't see a yellow triangle when viewing my Inbox, or when composing a new e-mail message. Could you explain what screen you're on, and where the yellow triangle is at? Could you provide a screenshot? Comet Tuttle (talk) 22:13, 21 April 2010 (UTC)

It's quite common for web pages to produce errors that can be revealed by clicking the yellow triangle. Firefox does this a different way, and you can see errors with Tools, Error Console. Both hide errors because they are so common and can generally be ignored, and I would recommend doing this. In the case of your page that you say "hadn't changed in two hours" it's possible that the session for the page had timed out and caused the error. --Phil Holmes (talk) 08:29, 22 April 2010 (UTC)

Nope, that never happens.Vchimpanzee · talk · contributions · 15:32, 22 April 2010 (UTC)

Create CD-Audio from DVD soundtrack

Hi, I have a Panasonic DVD recorder (DMR-EX75) which has a built-in Freeview tuner, so I can record both TV and radio programmes to the HDD, and then burn those that I want to keep to a DVD-R/RW, DVD+R/RW, or DVD-RAM. Depending on the disc type used, the programmes are recorded in either DVD-Video (IFO/BUP/VOB files) or DVD-VR (IFO/BUP/VRO files) format. If I have recorded a radio programme, the recording has a video component which is a piece of still text giving basic information like the channel it was recorded from. The only bit I'm interested in is the audio; but the Panasonic machine won't burn to a CD-R or CD-RW.

What I want to do is take the IFO/BUP/VOB files of the DVD-Video format from the DVD, strip the video information to leave only the audio, and burn to a CD-R or CD-RW, so that it can be played back in a regular CD player. My PC has a CD burner which will read any of the above disc types, but RealPlayer will only recognise those in DVD-Video format - it doesn't like those in DVD-VR format (recorded to a DVD-RAM). What software should I use on my PC to convert a DVD soundtrack into a playable audio CD? --Redrose64 (talk) 21:49, 21 April 2010 (UTC)

Typing "rip audio dvd" into Google (without the quotation marks) gives a large number of suggested solutions. I'd suggest investigating some of those and letting us know if you need further help. --Phil Holmes (talk) 08:25, 22 April 2010 (UTC)

April 22

Running Mac OS X software on Windows

Is there any way I can run Mac OS X .app files on Windows, like -- but not using the same method as -- WINE lets Windows programs execute on Linux, Mac OS X, and BSD? --72.87.89.95 (talk) 02:43, 22 April 2010 (UTC)

You could always run OSX in a virtual machine. [2] 121.72.202.170 (talk) 09:26, 22 April 2010 (UTC)

Legaly? —Preceding unsigned comment added by 85.183.20.88 (talk) 11:48, 22 April 2010 (UTC)

See Hackintosh. It's technically possible, with some work. It violates Apple's EULA, which might make it illegal (and might not, depending on jurisdiction, enforceability of EULAs, etc.). --Mr.98 (talk) 11:57, 22 April 2010 (UTC)

wiki markup

What is the wiki markup to cite articles on other wiki projects? 71.100.1.71 (talk) 03:56, 22 April 2010 (UTC)

See WP:CT -- kainaw™ 04:47, 22 April 2010 (UTC)

I can not find the current syntax for creating inline reference for a Wikipedia sister project.
In the past such references were entered as '''[[w/name of article]]''' .
What is the current syntax? 71.100.1.71 (talk) 05:29, 22 April 2010 (UTC)

I think WP:IW is what you are looking for. Winston365 (talk) 05:54, 22 April 2010 (UTC)

Here is how it is done. [[United States]] leads to the English language article, while [[:fr:États-Unis]] leads to the French language article. Similarly, [[:wikt:united]] leads to the definition of the word "united" at Wiktionary. Astronaut (talk) 23:55, 22 April 2010 (UTC)

server services

Seems like most servers have very upfront services like a time service or quote service. Do any of the server operating systems include a calculator service or similar type services? 71.100.1.71 (talk) 07:56, 22 April 2010 (UTC)

bc is a command-line accessible calculator. It would be easy to make this accessible over the network, if that was so desired. Nimur (talk) 12:15, 22 April 2010 (UTC)

I would tend to think there would not be much demand for this, because any computing device can easily be programmed to calculate something, whereas not every computing device knows what time it is. Comet Tuttle (talk) 14:09, 22 April 2010 (UTC)

There are quite a few irc bots that can do things like that (example). Turning one into a more generic socket listener should be straightforward, but I can't see why anyone would want to. If you've got a computer to connect to the server with, why not just run a calculator on it directly? There are of course also services like Google Spreadsheets, which could be viewed as fancy online calculators. 66.127.53.162 (talk) 22:27, 22 April 2010 (UTC)

Like other RFC's for testing and measurement purposes. 71.100.1.71 (talk) 10:53, 23 April 2010 (UTC)

Learning to write a compiler (or at least a language parser)?

At work, we have an application that requires users to write programming code in a relatively obscure language. This programming language is somewhat verbose, reminiscent of COBOL. Nobody likes this language so we want to create some sort of graphical front end that would allow users to define their programming logic without writing any logic (aside from mathematical formulas). The code that they write is relatively simple in that they're not full-blown applications. Basically, they write the equivalent of what typically goes inside of a function. For example, the users might write something like this:

//psueduocode
loop for each item in list
	if variable1 >= variable2 - variable3 then
		call pre-defined-function("error")
	end if
end loop

There's no OO or anything like that to worry about. The only thing we want users to have to write by hand are mathematical formulas, similar to the manner that users enter formulas in Excel.

The problem is that I've never written a compiler or a language parser. So, I want to learn how to create one from scratch.

So far, my Google/Bing searches haven't come up with a lot of useful information. I've found plenty of resources on how to use, for example, lex and yacc.[3] But I don't necessarily want to know how to use lex and yacc, I want to know how to create one myself from scratch. So, basically, I'm looking for a beginner's guide on how to create a language parser. Something that walks me through the process step-by-step.

So far, the best resource I've found are these lecture notes.[4] Unfortunately, it only briefly describes lexical, syntactic and semantic analysis and then jumps into using a pre-made tool.

Note that I don't need to generate any machine code. It's the language parser that I'm interested in.

I'm wondering if I would be a good idea to order university textbook on compiler design.

If anyone has any resources or advice, I'd greatly appreciate it. A Quest For Knowledge (talk) 13:31, 22 April 2010 (UTC)

Pretty much the standard textbook in this field is Aho, Sethi, and Ullman's Compilers: Principles, Techniques, and Tools (nicknamed The Dragon Book); if this has any failing it's that it doesn't have a lot of concrete code in a real language (it's deliberately trying to present ideas rather than acres of sourcecode). A popular alternative is Andrew Appel's books Modern Compiler Implementation in C, Modern Compiler Implementation in Java, and Modern Compiler Implementation in ML (pretty much the same book but written to meet the expectations of people familiar with those concrete languages). -- Finlay McWalter • Talk 13:42, 22 April 2010 (UTC)

If you are looking for some very simple examples, take a look at my course page for CSC519. It has a simple, hand-written C parser for a small, but Turing-complete language. Compiler discussion starts on page 61 or so of the lecture notes, the concrete example is discusses starting on page 144. --Stephan Schulz (talk) 13:54, 22 April 2010 (UTC)

In practice lexical analysis isn't very hard. Syntax analysis can be, depending on the language - you generally express the syntax formally in Backus–Naur Form, and then construct a parser (very often a LALR parser) to turn the token stream into an abstract syntax tree; as the LALR article notes, generating that parser from the BNF can be a bit scary (which is why so many people use a LALR parser generator like yacc to do it). With the syntax tree you have a reasonable representation of what (you think) the programmer "meant"; it's the basis of validation, interpretation, or code generation. -- Finlay McWalter • Talk 14:08, 22 April 2010 (UTC)

You might be able to solve the problem of people not wanting to type in verbose repetitive commands by simply using an editor with an auto-complete function. Or, it could work like a wiki editor and have icons to add predefined content. So, you may not need to write your own compiler. StuRat (talk) 14:09, 22 April 2010 (UTC)

Wait -- lex and yacc are tools for creating compilers; you probably don't need to create a new lex and yacc (there are a lot of different compiler-compilers out there if yacc doesn't do what you want). You feed a description of the language into yacc, and it creates a C program that parses the language.

You might want to consider embedding an existing language, rather than writing your own. It might be harder (but might be easier!) to do than to write an ad-hoc language, but growing an ad-hoc language can be very difficult. I understand that Lua is often used for embedding. You can also embed Python, and probably a whole lot of other nice languages. (This also has the advantage that complete documentation for the language will already exist.) Paul (Stansifer) 14:16, 22 April 2010 (UTC)

Thanks to everyone for their help and suggestions. I have a lot of reading to do this weekend. :) A Quest For Knowledge (talk) 11:59, 23 April 2010 (UTC)

You should read Structure and Interpretation of Computer Programs, which you can view online for free. But frankly, writing your own extension language doesn't sound like the right thing you should be doing with your work time for a production project. You're much better off embedding something that's already designed and used, like Lua or Python or even Javascript. Writing a compiler as a personal project is great fun, of course. Every programmer's dream used to be to write the Great American Compiler. A newer and more theoretical book is Practical Foundations of Programming Languages[5] by Robert Harper. 69.228.170.24 (talk) 07:10, 24 April 2010 (UTC)

c program (English dictionary)

I am a b tech 2nd semester student. I have to prepare a mini project in data structures in c having lines of code=1500!

I wish to make a normal english dicitionary using file handling n linked list..can anyone of you suggest me proper coding for that as i am a beginner in C and lack few general concepts..Supriyochowdhury (talk) 14:03, 22 April 2010 (UTC)

I hate program assignments that specify the number of lines, as this encourages inefficient coding.

You will need a large (100,000 ?), alphabetical list of English words and definitions in a data file (CSV format would be good). You need some easy way to get this file, as obviously you can't type it in. Then I suggest a binary search for the word that's typed in.

A simple look-up program seems more like a 50 line program than 1500, though. Now, if you add code to allow you to edit dictionary entries, add them in alphabetical order, delete them, provide links to other entries, synonyms, antonyms, use different dictionaries (US vs UK English) etc., then you might get to 1500 lines.

Also note that the entire dictionary may be too large to fit into memory, so you might want to break the data files down, by first letter of the word, or some other method. StuRat (talk) 14:19, 22 April 2010 (UTC)

C programs are whitespace-insensitive, so the number of lines of code are literally irrelevant. It is possible to have 1500 non-blank lines, each containing a single character or keyword, at the expense of readability. Similarly, one could conceivably write a very large project as a single line of C code (at the expense of readability). It would be better to specify the features you need than to specify an arbitrary number of lines. In fact, you can write any C program, and then add or remove newline characters until it is exactly 1500 lines. If a professor is being intentionally pedantic, they should specify "at least 1500 lvalue assignments" - which would be similarly meaningless from a design point of view, but at least has a precise meaning in terms of implementation. If you are seeking additional features for your dictionary program, you might want to write a text-processing utility to scan a file, analyze its contents, and reprint them so that the contents occupy exactly 1500 lines. When you are done, test it by running that processor on a copy of your source-code, and then recompile the output. You can market it as a "1500-line-dictionary-generator," with the added bonus feature, "works on non-dictionary text files too." Nimur (talk) 15:21, 22 April 2010 (UTC)

In direct response to the original poster, consider reading linked list, and binary search algorithm (useful for dictionary lookup - so plan your linked list implementation carefully!). Also be sure to check out the excellent wikibook, C Programming, particularly the introductory section on Strings and the in-depth string manipulation chapter. This is the toolkit that a C programmer has for text processing - it is very powerful, and it is good to know what is already available so that you don't waste time writing it yourself. And while we're providing useful links, here is Project Gutenberg's free, free version of an English dictionary: Webster's Unabridged Dictionary pg.1-100, pg.100-200; and the unabridged version in many separate text files. Nimur (talk) 15:36, 22 April 2010 (UTC)

If you are trying to come up with a project, I suggest this as it is a dictionary-like project, will fill the number of lines of code (if done well) and is somewhat useful. First, get a dictionary of words that you want. By "dictionary", I simply mean a list of words - no definitions. Now, use an indexing algorithm like soundex to sort the words into a hash table of arrays. With the hash of word indexes, you can perform the following rather common function. A user types in a word. You index that word using the same algorithm you used to index the dictionary. You now know which array of words to use because you go to that index in your hash table. Next, use a similarity metric (like a modified Levenshtein distance) to measure the similarity of the word the user typed to every word in the array. If you have a perfect match, no problem. If there is no match, show the best matches as a "did you mean" list. -- kainaw™ 16:04, 22 April 2010 (UTC)

The other answers have provided good guidance on your project, but first you might want to seek clarification from your professor... did they say "write a program of exactly 1500 lines" (IMHO, that sounds like a lot to demonstrate you have learned enough about data structures), or did they say "write a program of no more than 1500 lines" (which sounds like the kind of thing a professor would say). Remember, your professor has got to read and evaluate your program, and those of the other students too, and they only have a short time in which to do that. Astronaut (talk) 00:09, 23 April 2010 (UTC)

Shortcut

I want to make a shortcut to a program that will remember the program when used on use drive and different drive letters. However, standard windows shortcuts do not understand "./" and give an error when I use that. Are there any third party programs that can make persistent shortcuts that work on any drive letter etc and understand "./"? 82.43.89.71 (talk) 14:43, 22 April 2010 (UTC)

Perhaps you could write a batch script, or a simple Windows script, to check for the correct program location? Then, your shortcut would point to the same location (the script); the script could intelligently redirect and execute the desired program from a set of possible locations. Nimur (talk) 15:07, 22 April 2010 (UTC)

if exist e:\program.exe    e:\program.exe
if exist f:\program.exe    f:\program.exe
if exist g:\program.exe    g:\program.exe

This script will check for the program.exe in several locations and execute it only if it exists. You can modify it (fairly straightforwardly) and save it as a .bat file. (Note that this script does not do any kind of error-checking or verification; you could add such features as you need). Nimur (talk) 15:10, 22 April 2010 (UTC)

Are you sure you can't map the drive to a particular drive letter? You can use diskmgmt.msc to set drive letters, and if you choose a letter far out in the alphabet it shouldn't conflict with any other drives. I do not understand your reference to "./" but to refer to something on the same drive as the current directory, you can use for example "\windows\notepad" to execute Notepad from a working directory anywhere on drive C. Jørgen (talk) 19:48, 22 April 2010 (UTC)

USB drives on other peoples computers almost always have different drive letters ranging from E:\ to K:\ and anywhere in between. Often these computers also have limited rights so I can't just start mapping drive letters and stuff. The reference to "./" just means in computer talk the current directory. But unfortunately as I said Windows shortcuts don't understand this 82.43.89.71 (talk) 06:26, 23 April 2010 (UTC)

[6] while rather old didn't find anything much more useful then discussed here. The thought did occur to me that if the USB drive is NTFS you could use an NTFS symbolic link for most purposes. Also not really a solution but I'm guessing if the path changes Windows may still be able to find the new path if you use the find target option, but this requires more clicks and other such issues. BTW, I wouldn't use ./ on Windows. Since Windows uses the reverse slash, some programs may understand it, but many will not (*nix based programs like Cygwin may prefer or require it of course). Try .\ instead although this won't help with shortcuts. Nil Einne (talk) 07:49, 25 April 2010 (UTC)

Alternate fix for this Infamous Windows Annoyance: One way around this annoyance in Windows is to create a standard directory structure that you always use 100% of the time. The trick is to set up something that you are guaranteed to have access to. For example, create a c:\myhome directory.

Then, for the second part of this workaround, you use symbolic links, so that whatever drive you are interested in is always reachable from c:\myhome. The symbolic links will make it so accessing c:\myhome is the same as accessing e: f: g: or whatever. NoClutter (talk) 22:55, 26 April 2010 (UTC)

GraphViz + Doxygen

I want to generate a Doxygen doc, but my starting point is a GraphViz graph (.dot). I have both programs installed and working.

The end result should be something like [7], where the nodes have html links. How can I do it?

An example of what I want can be seen at the Doxygen page here. I need that, but with hyperlinks.--ProteanEd (talk) 16:02, 22 April 2010 (UTC)

Download countdown timer

How would a download counter timer be programmed? For example, when you're downloading something on the computer and it sometimes says 'time remaining' which changes as the download progresses. How does the computer know roughly how long the download will finish? Please do not be too technical, I know some things about computers but not in-depth programming techniques. Chevymontecarlo. 19:00, 22 April 2010 (UTC)

How is a download timer usually programmed? Poorly.

That out of the way, the simple approach, is to take the current download speed (say, 10kilobytes per second) and divide by the size of the portion of the file not yet downloaded ( say, 1000 kilobytes ) and you've got your answer in seconds. (In this case, 1:40).

The problem here is that your download speed can fluctuate. Often wildly fluctuate. The trick is to try to use some sort of intelligent averaging technique. APL (talk) 19:09, 22 April 2010 (UTC)

Obligatory xkcd link: The author of the Windows file copy dialog visits some friends. Comet Tuttle (talk) 19:17, 22 April 2010 (UTC)

APL - yes it seems that the estimates are wildly inaccurate when the download starts and then as the download progresses the estimates get better. Thanks for that overview. Chevymontecarlo. 19:23, 22 April 2010 (UTC)

Comet Tuttle - hahah yeah lol! :D Chevymontecarlo. 19:24, 22 April 2010 (UTC)

Moving average is one of the simplest techniques. By selecting a proper parameter, even the simplest type - a "single-tap" moving average - can be reasonably accurate. More sophisticated estimators may use heuristic or other averaging algorithms to generate more accurate guesses. No matter how intelligent an algorithm is, it can only be reasonably accurate if there is a certain degree of uniformity or predictability to the transfer speed. Nimur (talk) 19:27, 22 April 2010 (UTC)

Some TLDs are valid DNS names by themselves, but Mozilla Firefox doesn't know it

I learned today that some TLDs are valid DNS names by themselves, and thus also valid URLs. For example, to is a valid DNS name, with the IP address 216.74.32.107.

As such, http://to/ is a valid URL, consisting of the front page of a URL shortener. But if I enter that URL into Mozilla Firefox, it absolutely insists on instead taking me to http://www.to.com/ which is a some sort of German industrial company. I absolutely hate it when programs think they know what I mean better than I do. How can I make Mozilla Firefox realise that when I say http://to/ I mean to and not www.to.com? JIP | Talk 20:42, 22 April 2010 (UTC)

The page you're talking about is at http://to./, not http://to/. Typing to. into the address bar works fine in my Firefox. Algebraist 20:50, 22 April 2010 (UTC)

Does this mean I have misunderstood the relationship between DNS names and URLs, that http://insert DNS name here/ is not a valid URL for all valid DNS names? host to has no problems finding the server hosting the URL shortener, but wget http://to/ doesn't work any better than Mozilla Firefox. wget http://to./ works, though. JIP | Talk 20:56, 22 April 2010 (UTC)

On the same linux platform as below, nslookup to, dig to, and wget to all work as expected. -- Finlay McWalter • Talk 20:59, 22 April 2010 (UTC)

Firefox 3.5.9 (ubuntu-linux=canonical) is perfectly happy with one entering simply "to" into the url box, or clicking on http://to/ and both take me to the to URL shortening service. Opera, Chrome, and Konqueror on the same platform also work fine. I don't need to add the auxiliary period that Algebraist mentions. Perhaps you have some extension or toolbar that is "helping"? -- Finlay McWalter • Talk 20:52, 22 April 2010 (UTC)

My browser is now behaving as you describe. When I made my post above, it failed to find anything when clicking the link and (understandably, since it thought http://to/ was invalid) went to www.to.com when I entered to. How odd. Algebraist 21:00, 22 April 2010 (UTC)

No, I use FireFox 3.5.9 on Fedora 12, with no "helpful" extensions. Entering to into the location bar takes me to a Google search. Entering http://to into the location bar takes me to the http://www.to.com site. Clicking on the link to http://to gives me an error message about Firefox not being able to find the server at "to". With the period, everything works. Entering http://to./ (with or without the trailing slash) or clicking on the link takes me to the URL shortening service. Is this some problem with Firefox 3.5.9? JIP | Talk 21:01, 22 April 2010 (UTC)

Then it may be your ISP's DNS server that's trying to be helpful. Find the IP of that server (your router will know), call that X, and compare the results of:

          dig @208.67.222.222 to
          dig @X to

where that first IP is the OpenDNS server. If X's reply is to google or whatever, there be the problem. -- Finlay McWalter • Talk 21:13, 22 April 2010 (UTC)

Both commands give me the exact same result. So it's not the DNS server that is the problem, but the applications. JIP | Talk 15:20, 23 April 2010 (UTC)

Firefox has several features which override your exactly-typed URL, including: Smart Keywords, Searching from the Location Bar, and Domain Guessing. Each of these must be disabled in order to guarantee that your Firefox will not "assume" anything about your URL. I have ranted about this many times: most recently, it seems, December 2009 - with instructions on how to disable these annoyances. I regularly surf on a private network with a privately operated DNS system, and it is extremely irritating that Firefox assumes that if I typed nimur, I want http://www.google.com/search?q=nimur. I actually wanted http://nimur, which is perfectly valid on my network (while "google.com" does not exist and yields a "server not found" error). Nimur (talk) 02:18, 23 April 2010 (UTC)

After looking it up with [8], [9] will work because "to" is now in your DNS cache, associated with an IP address. Assuming you're on Windows, you can open a command prompt and run "ipconfig /flushdns" (on linux restart nscd), which will clear your cache, and Firefox will again forget that it's a valid URL. Interesting stuff. Also, in case anyone wasn't aware, putting a dot at the end works because it explicitly states that you're typing a FQDN, not an unqualified hostname (which your resolver will append your domain suffix to). Indeterminate (talk) 08:57, 24 April 2010 (UTC)

What do you call the yellow triangle?

[10]

Occasionally it appears in the lower left corner of the screen beside the message "Done, but with errors on page".Vchimpanzee · talk · contributions · 20:58, 22 April 2010 (UTC)

It is a generic warning icon. -- kainaw™ 21:39, 22 April 2010 (UTC)

It is probably derived from warning signs used for automobiles. --Mr.98 (talk) 21:49, 22 April 2010 (UTC)

Wikipedia doesn't have anything about its use with computers?Vchimpanzee · talk · contributions · 22:35, 22 April 2010 (UTC)

No, because any software application could use it in a different way. What browser are you using that shows you it? (Go to the Help menu and choose "About Internet Explorer..." or "About Mozilla Firefox" or whatever.) Comet Tuttle (talk) 23:13, 22 April 2010 (UTC)

In Windows it is part of the generic message box icon set (along with the X in a red circle, question mark in a speech bubble, and "i" in a speech bubble). It's one of a couple icons programmers can choose to convey their messages. It doesn't have specific, system-wide use, other than generally meaning "something important but not necessarily critical." --Mr.98 (talk) 00:40, 23 April 2010 (UTC)

The Windows development environment calls it both the "warning" icon and the "exclamation" icon - both of which make sense. --Phil Holmes (talk) 08:58, 23 April 2010 (UTC)

Variations of this are common: commons:Category:Yellow triangles. PrimeHunter (talk) 18:12, 23 April 2010 (UTC)

(Edit conflict) I went to my computer's help screen and typed in "yellow triangle" but didn't get anything useful. "Done, but with errors on page" helped even less. That's when I most often see it. "Done" didn't give me anything.Vchimpanzee · talk · contributions · 18:14, 23 April 2010 (UTC)

Again, could you tell us what browser you are using? Also, could you point us to one of the web pages giving you this error? The problem is almost certainly just going to be buggy HTML code on the web site you are visiting; this is all over the Web, due to sloppy developers. Comet Tuttle (talk) 20:13, 23 April 2010 (UTC)

Internet Explorer 8, but I think I saw it on Firefox too at a library. The problem refers back to this question, but I was wanting to research the symbol just out of curiosity.Vchimpanzee · talk · contributions · 20:18, 23 April 2010 (UTC)

Or try this.Vchimpanzee · talk · contributions · 21:17, 23 April 2010 (UTC)

OK, I visited that web page and I do see the yellow triangle error icon in Internet Explorer. As someone mentioned in the previous thread you pointed to, and as I mentioned above, this just means there is an error in the source code of the web page. This is because the coder who wrote the web page was sloppy. (It actually could be the fault of lack of testing some unusual case; but it's probably the coder's fault.) It's nothing to worry about on your end, though it might indicate that the web page is not working the way the coder wanted it to work. Comet Tuttle (talk) 22:53, 23 April 2010 (UTC)

Additionally, you can double click on the "Done, but with errors on page" message in the status bar to bring up a dialog box that shows the errors on the page. (By the way, the error dialog box refers to the icon as the "warning icon" when it tells you how to double-click the status bar to show the message in the future.) --Bavi H (talk) 07:12, 25 April 2010 (UTC)

Thanks, I was told to do that here and in some cases it has been helpful. My main purpose was to find out what it was called.Vchimpanzee · talk · contributions · 18:50, 25 April 2010 (UTC)

Kenny Kerr

Resolved

What is the difference between this and this Kenny Kerr? Is it the same person? --Andreas Rejbrand (talk) 21:32, 22 April 2010 (UTC)

I think it is the same person. --Andreas Rejbrand (talk) 23:29, 22 April 2010 (UTC)

April 23

Writing my own programs for iPhone

An earlier discussion centred around Apple's refusal to allow Adobe Flash on the iPhone platform and the non-availability of Flash on Apple's App Store. One answer proposed porting an open-source Flash player to the iPhone. But, that raises an interesting question. If you were to write your own iPhone program, how would you get it installed onto your (non-jailbroken) iPhone if the App Store is the only way to get any app on the iPhone? Astronaut (talk) 00:35, 23 April 2010 (UTC)

According to our article on the iPhone SDK, you can develop them off-line (not on an iPhone) with an "iPhone simulator", but if you want to load them onto a device (even just your own), you have to pay an "iPhone Developer Program fee." (Can I soap-box for a moment just to say how disturbing I find it that geeks who are normally up in arms about big corporations determining how they use their computers are willingly accepting this kind of thing? This is about as far away from a free-software ideal as you can get.) --Mr.98 (talk) 00:51, 23 April 2010 (UTC)

The Free Software Foundation has been campaigning against the iphone ever since there was an iphone. That's about as "up in arms" as can be, lacking the budget for an actual army. 98.226.122.10 (talk) 01:47, 23 April 2010 (UTC)

I'm actually a little offended at the insinuation that Apple fan-boys are just like us free-software enthusiasts. We activists who develop and promote free, free software are a little too scruffy and unshaven to fit into Apple's target-market! Just because some rimmed-glasses turtleneck with an iPhone calls himself a "technology enthusiast," you can't lump him in with the rest of us! At least, not until they complete the rite-of-passage: releasing something useful and potentially profitable under a free license like the GPL, instead of through a commercial channel. Nimur (talk) 14:26, 23 April 2010 (UTC)

Well, if you only want to develop for the iPhone (not the iPad or iPod touch) you can register for free, otherwise it's $99/year. It also requires that you run the SDK on OS X Leopard or newer; no other operating systems are supported. Also, Apple recently stated that all applications must be written in "Objective-C, C, C++, or JavaScript". Indeterminate (talk) 02:00, 23 April 2010 (UTC)

I've criticized Apple in several forums. But on the Apple forum, they just censor me. They removed a comment I made that Steve Jobs is trying to increase sales on the iTunes video store by killing free streaming Flash video. But, suspiciously, they left the rest of my post intact. ;-). Electronic criticism is about the limit of what I can do. Adobe is the only company with enough power to hit back hard. They appear to be preparing a lawsuit. And if they were to discontinue Photoshop and Dreamweaver for the Mac, and deny Apple the right to use the PDF and Flash Player in Mac OS X, they would do some serious damage to Apple's market share. But I fear that both companies are too concerned with profit to take any courageous, principled steps at this point in time.--Best Dog Ever (talk) 02:16, 23 April 2010 (UTC)

And yet when you point that out to the Apple fanboys, they call you all sorts of names, "wintard" being the most popular insult. I've nothing against Apple products at all, but I don't like it when people freely call out Microsoft for all the crap they've pulled over the years, yet they refuse to hear any criticism on Apple having its own flaws. Every company has its faults, one shouldn't have the luxury of being able to sweep theirs under the rug. In fact, the whole point of criticism is to demand that they make their products better to use. 24.189.90.68 (talk) 08:43, 23 April 2010 (UTC)

It is these "must use iTunes" and "must develop on Mac OS X" restrictions which are the main reason why I haven't rushed out to buy an iPhone. Astronaut (talk) 10:35, 23 April 2010 (UTC)

Two words: HTC Desire. After all, it is the best phone in the world according to techradar. 131.111.185.69 (talk) 12:51, 23 April 2010 (UTC)

Funnily enough, I read a magazine review of that very phone just this afternoon, and a friend of mine has good things to say about HTC products. Think I'll check it out. Astronaut (talk) 22:46, 23 April 2010 (UTC)

We have to vote with our feet. Just say no to closed systems - the Android phones are every bit as good (many would argue "better") and you can develop for them on Linux, Mac or Windows. The full developer toolkit includes a phone emulator and is free. The Android runs Linux - and most of the source code is freely available. It has proper multitasking (not like the crappy system Apple kludged onto the iPhone as an afterthought). You don't have to get permission from almighty Apple to get your App onto the market. It's a great platform. SteveBaker (talk) 18:53, 24 April 2010 (UTC)

lossless ogg vorbis editing?

I have an Ogg Vorbis audio file that I'd like to losslessly extract a clip from. By that, I mean Vorbis is already lossy compression, and editing with audacity seems to introduce further loss by uncompressing and recompressing the vorbis file. I'm hoping to just select a bunch of the compressed frames from the input file and copy them to the output file. Is there a simple way to do that? Thanks. —Preceding unsigned comment added by 66.127.53.162 (talk) 08:46, 23 April 2010 (UTC)

The Oggz tools (specifically oggz-chop, for your task) can do this and some other lossless Ogg editing tricks. They're command line tools, but they should be quite straightforward to use (at least for simple things like cutting files) if you have even a little bit of experience in using the command line. I'm not particularly familiar with equivalent GUI tools, but a bit of Googling turned up Ogg Cutter for Windows. —Ilmari Karonen (talk) 20:23, 27 April 2010 (UTC)

Mac OS X Updates Download

Is there a direct download for Mac OS X Updates? A friend of mine is asking this because his Apple Updater (Leopard) is really slow at the moment and sometimes crashes. Is there any way he can bypass the updater and download directly to his Mac (thinking about it now, actually, I have the same problem with mine (Tiger)). --KägeTorä - (影虎) (TALK) 08:58, 23 April 2010 (UTC)

You can get the latest updates from Apple's website, I think. Try using the search bar on there- I can't find the direct link to it. Chevymontecarlo. 11:55, 23 April 2010 (UTC)

Cheers. I looked on there and only found info about the most recent update, not the update itself. I'll take a look again. --KägeTorä - (影虎) (TALK) 20:53, 23 April 2010 (UTC)

Oh, I thought you could grab the updates directly. Sorry about that, but I'm fairly sure you can, somewhere. Chevymontecarlo. 07:36, 24 April 2010 (UTC)

[11] - click the Download button to get the .dmg. (first result for "download os x updates" ;) Indeterminate (talk) 07:56, 24 April 2010 (UTC)

Deploying software through Active directory

Hi I am trying to publish Adobe reader through active directory.

I have configured the Group policy in user configuration->Software settings->Software installation so that with the relevant .msi. \\<<my name>>-serv\programs\AcroRead.msi, and in deployment state published.

However this policy setting does not show in Resultant Set of Policy, and the software is, presumably for the same reason, not availiable for installation in the clients. What am I doing wrong?

To eliminate one possible source of error; the group policy is placed in the top of my domain, and other changes that I make in it does show up in Resultant set of policies. 213.161.190.227 (talk) 09:02, 23 April 2010 (UTC)

Motorola Milestone and Android 2.1 update

I'm in the Netherlands, with a Motorola Milestone. This week I received the Android 2.1 update 1, OTA, and installed. Seems that worked, as new features are functional. There is now a 'voice dialer' program, which is working. All good. What I can't figure out how to turn on, is the 'speech to text' feature of the keyboard, or in text boxes. There should now automatically be a microphone icon on the keyboard, and in the google quick search text box, but it isn't there. I found one advice by googling around that the settings are in "language and keyboard>android keyboard", but in my language and keyboard, I have 'motorola keyboard' not android keyboard, and no setting that I can discover for turning on or off the microphone/'speech to text' feature. I have been on the Motorola website and other Android blogs, but w/out success so far. Thanks if you can help. —Preceding unsigned comment added by 80.101.134.43 (talk) 09:33, 23 April 2010 (UTC)

According to http://www.heise.de/ct/hotline/FAQ-Android-980631.html (German, Google translation here [12]): [...]on the other hand, some innovations are disabled despite Android 2.1: The Motorola Milestone is missing, for example, the system-wide voice, the HTC Legend shows no Live background.

Note to U.S. readers: The Motorola Milestone is a GSM/UMTS version of the Motorola Droid. -- 78.43.60.58 (talk) 11:13, 25 April 2010 (UTC)

Does this exist?

I'm looking for a mouse, doesn't matter where from, that is wireless,and has a battery pack. But when it's dead I'd like to be able to plug in the mouse and use it wired until it finished charging. Something like the Xbox_360_Controller#Play_And_Charge_Kit. Does this exist? Chris M. (talk) 15:31, 23 April 2010 (UTC)

A search for "wired wireless mouse", returns only the Razer Mamba. ---— Gadget850 (Ed) ^talk 16:35, 23 April 2010 (UTC)

I think that the Logitech gaming mice [e.g. this one.] can be used while they are charged. --Andreas Rejbrand (talk) 17:53, 23 April 2010 (UTC)

I have two mice (a wireless and a wired device). Both connect over USB. Every operating system I have used, except Mac OS X, behaves exactly as you would expect - both mice can be used simultaneously; if one sits dormant, the other controls the mouse cursor. This is a cheap workaround - a wired mouse can be under $5 - so this may be the most cost-effective solution (if not cheapest in terms of desktop real-estate). Nimur (talk) 22:14, 23 April 2010 (UTC)

As has already been mentioned, Logitech Performance MX & the Razer Mamba have this. As these are high end gaming mice, they are not cheap and if you don't game, you may find a lot of their features useless. The Microsoft Sidewinder X8 (which is also a highend gaming mouse but tends to be cheaper at least where I live) also has this. The modified Logitech MX1100 part of the Logitech Wave Pro (not Wave) mouse+keyboard set is another one but bear in mind the original/stand alone Logitech MX1100 does not. All of these except for the Microsoft use micro USB cables I believe (which may be useful if you have a phone or something else that uses micro USB) to connect the mouse while the Microsoft has some magnetic thing which is supposed to be easy to quickly connect (as I said it's designed for gamers). The Logitechs are both part of their unifying receiver range and the MX1100 in particular has an AA battery but I'm not sure how easy it is to remove (there's the risk someone may put a non rechargable battery in it then plug it in, but then that's common with many DECT phones and some other similar devices). Nil Einne (talk) 07:59, 24 April 2010 (UTC)

I keep a spare set of rechargeable batteries on my desk, so when the batteries in my mouse are flat, I can immediately swap them out. 121.74.167.214 (talk) 08:10, 24 April 2010 (UTC)

Why not just buy a second mouse? Cheap USB mice are about $10 to $15 - keep it in your drawer and plug it in when your fancy wireless mouse craps out. SteveBaker (talk) 18:48, 24 April 2010 (UTC)

MSN plugin Logitech G-19 keyboard

Where can i find a msn plugin for the screen on the g-19 keyboard? —Preceding unsigned comment added by 83.183.172.203 (talk) 21:19, 23 April 2010 (UTC)

April 24

Forget password and not getting E-mail

Hello !!

I have forgot my Wikipedia password ( username : manoj_meena ) I tried resetting it with "Mail me my password" method but i am not getting any mail on my account.

can you please let me know which e-mail account is associate with my Wikipedia account so that i can check those mails there. It may be issue as i earlier had my college official e-mail attached to most of my accounts but as not i am graduated from there that e-mail address is deactivated.

What should i do ? any sort of help will be appreciate.

thank you

Regards

- Manoj Meena

<contacts removed> —Preceding unsigned comment added by 203.78.217.151 (talk) 00:25, 24 April 2010 (UTC) 

Unfortunately, if you do not remember the e-mail address you associated with your account, or otherwise do not have access to the address, there is nothing anyone can do. We do not know and cannot find out what the e-mail address was, nor can anyone here reset your password for you. Unless you miraculously remember what the e-mail address was, you will have to create a new account. If you have any further questions that directly relate to Wikipedia, please post them at the Help desk; this page is for general knowledge questions. Xenon54 / talk / 00:36, 24 April 2010 (UTC)

All we can see is that the account User:Manoj meena was created 27 August 2006 [13] and has an email address associated with it. We cannot see the address. The account has no edits so creating a new account is perfectly OK. PrimeHunter (talk) 01:10, 24 April 2010 (UTC)

Another account User:Manoj Meena was created 24 September 2006.[14] They are different accounts and may or may not have different passwords and different email addresses. We cannot see it. As an administrator I can see that User:Manoj Meena made edits to the deleted page VSOID on 3 February 2010. PrimeHunter (talk) 01:17, 24 April 2010 (UTC)

How's my motherboard look?

Hello! I have an HP dv 9000 laptop, which has been noted by the company to have inadequate fan controls to cool all of the internal hardware, and I believe my video card has been damaged. When I try to boot to Windows, I get a BSOD caused by a fatal error at my video card's driver. When I delete the driver, Windows boots up fine (albeit with very ugly graphics) on an external monitor, with the disk drives perfectly accessible. I've uploaded a few pictures of the internal components to my userpage (didn't want to clog up the RefDesk with them). I know C is the video card, but not quite sure what A and B are. They were all connected to the heat sink. Do any of them show signs of physical damage from overheating? Is it possible for components to be damaged without showing signs? Thanks for any help or advice. (And, yes, I tried the newest video card driver, and reverting to an old one; both caused fatal errors.)--el Aprel (^facta-_facienda) 01:21, 24 April 2010 (UTC)

No idea what A is, but A and B look pretty scorched to me. Are all HP laptops notorious for overheating, or just the particular model you have? 24.189.90.68 (talk) 02:14, 24 April 2010 (UTC)

A is the CPU and B is the northbridge chip. They do look a bit scorched, but it's still possible for them to be damaged even if there are no visible signs. To me it does sound like a fried video chip is a likely possibility. Winston365 (talk) 03:18, 24 April 2010 (UTC)

24.189, have a look at this website from HP. It talks about the models in question. I'd also like to note that A may look worse than it actually is; that burnt metallic stuff at the top was melted off from a conductor on the copper rod to the heat sink. When I opened A up, the CPU looked fine on the inside. What seems strangest to me is that dark ooze around A and B. It's dry, but is it supposed to look like that? Also, should I be concerned that A and B (the CPU and northbridge, as identified by Winston365) are damaged too? The computer runs fine with poor graphics with the help of an external monitor and no videocard driver, and judging by how important the CPU is, I would guess you would not see this much functionality if it was damaged.--el Aprel (^facta-_facienda) 04:08, 24 April 2010 (UTC)

The metallic stuff on the CPU is probably just thermal paste. It is not unusual for some to stick to the chip and some to the heat sink when they are separated, and doesn't indicate anything actually melted. The dark ooze you see appears to just be an epoxy used to affix the chip, also nothing to worry about. There does seem to be other discoloration around B that does look a bit like heat damage though. I agree that if it was a CPU problem it's very unlikely the computer would continue to function normally apart from the graphics. I'm not sure if the northbridge could cause that, I haven't seen it happen, but I suppose it's possible. Winston365 (talk) 04:50, 24 April 2010 (UTC)

Agree with Winston that A doesn't look abnormal. The 'ooze' is likely simply the epoxy to attached the chip. I think I've even seen a core like that before personally and it's easy to find pictures of similar cores [15] [16] [17]. It tends to stand out more when the core is large relative to the ceramic layer such as in mobile CPUs, for obvious reasons and obviously various from batch to batch and probably factory. B does look a bit odd Nil Einne (talk) 06:47, 24 April 2010 (UTC)

For future reference, the three biggest chips inside a laptop is the CPU, northbridge and graphics. The CPU can be identified by the fact that it is attached to a socket and not directly soldered. The graphics can be identified by the word Nvidia. 121.74.167.214 (talk) 08:08, 24 April 2010 (UTC)

HDTV stuck blue pixel

I have a brand new 26-in. RCA LCDTV, about 20 minutes out of the box, and there's a stuck blue pixel on it. What do I do? --Lazar Taxon (talk) 06:21, 24 April 2010 (UTC)

Ugh. We have an article, which stuck pixel does redirect to. Some manufacturers allow a return and exchange, and others have a stated minimum (for example, you need 5 stuck pixels in order to return the TV). Comet Tuttle (talk) 06:44, 24 April 2010 (UTC)

If the pixel happens to be near the edge, perhaps you can adjust the display size to not include that pixel or physically cover that area with black tape. I use the tape method to hide a line of frenetically flashing digital dots at the top of my TV. StuRat (talk) 11:48, 24 April 2010 (UTC)

Check with the store— most big-box places will swap it outright within a certain number of days. ---— Gadget850 (Ed) ^talk 16:46, 24 April 2010 (UTC)

Mr. Do's Wild Ride

I remember earlier posting to the reference desk about some computer game I played at my cousin's house in the early 1980s, but couldn't remember what it was. I had a look at the computer game articles on Wikipedia, and saw that Mr. Do's Wild Ride comes the closest to my (faint) recollection. But according to the article, the game was never released for the Commodore 64, which my cousin had. Is it still possible that a Commodore 64 version of the game somehow exists? JIP | Talk 06:43, 24 April 2010 (UTC)

Did the screenshots resemble the ones at arcade-museum.com? Could it have been one of the other games in the Mr. Do series? Comet Tuttle (talk) 07:08, 24 April 2010 (UTC)

Looks like the first game in the series Mr. Do! and the second Mr. Do's Castle were ported to Commodore 64, so you may be thinking of one of those. Winston365 (talk) 07:14, 24 April 2010 (UTC)

No, it was specifically Mr. Do's Wild Ride that invoked the memory. The screenshots did seem to match my recollection, with the tracks and the bumper cars. It was specifically not either of the first games. JIP | Talk 07:27, 24 April 2010 (UTC)

fast xml processing?

I want to process some large (6TB) XML documents, no prize for guessing what they are. Expat is supposed to be pretty fast, but my test app only gets about 3 megabytes/sec through it, which means that parsing the document will take months all by itself. I see there are some other libraries like vtd-xml that read the document into memory, which only is practical for smaller documents. I guess I can bite the bullet and write some custom C code but I don't understand the obstacle to writing a SAX-like parser that's simply extremely fast. I guess I will try libxml2 but from what I've heard, it's about the same speed as expat. Also, all these libraries that I know of handle the document serially; it would be nice if there could be some multi-threaded readahead to get more speedup (I have a quad core processor). I wonder if anyone has any suggestions. Thanks. 69.228.170.24 (talk) 08:24, 24 April 2010 (UTC)

Reading ahead would only help if you had multiple disk drives (so each can read simultaneously) and the memory to store the data. With a 6 TB file I would assume that it must be broken down into at least 3 pieces on 3 hard disks, but you're obviously going to overflow the memory quickly. What type of processing do these documents require ? Like any large task, it will help tremendously if you can break this down to small tasks. In this case, if you could take maybe 1 GB chunks of the document at a time (assuming you have maybe 2 GB of memory available), finish with each, then go on to the next, you would have a much faster program.

Be sure to code the program so that it can be restarted if the program stops, since this is all but inevitable over such long time frames. If you post the code, we might be able to point out any inefficiencies in the way it processes the data. StuRat (talk) 11:34, 24 April 2010 (UTC)

The file has a huge amount of redundancy and compresses down to about 30gb on disk. The idea is to uncompress and parse and process it on the fly. In case it wasn't obvious, it is a wikipedia meta history dump. The first thing I'd want to do with it is split it into smaller chunks that I can process in parallel, and gather various sorts of stats. My experience with this kind of thing though is it always ends up having to be done more than once, so month-long tasks aren't appetizing. It occurs to me that I can do some low-rent hack to mark out large sub-documents (article revisions) and then process the sub-documents with one of the fast in-situ xml packages that I've been able to find. After that I may be able to do further processing with a hadoop cluster. My expat bnechmark just reads a few million events and ignores them, but even doing nothing, it's much slower than I want to wait for. If I rewrite it in C it will be faster, but still too slow, and I was hoping to use more modern languages for this. 69.228.170.24 (talk) 11:51, 24 April 2010 (UTC)

The obvious solution here is to find a way to do the processing directly on the compressed format, without decompressing and recompressing it. You still haven't said what type of processing you need to do. StuRat (talk) 12:02, 24 April 2010 (UTC)

Processing the compressed format sounds completely impractical. My first goal is just to figure out how to even handle the volume of data, but as an example of a processing task, I'd like to look at statistics about edits from IP addresses to biographies of living people (User:Casliber had asked about this). 69.228.170.24 (talk) 12:12, 24 April 2010 (UTC)

OK, let's take that as an example. First, you might want to look for the "Category:Living people" tag. Hopefully, that will always look the same, once compressed. If you find that, then look for a compressed IP address. Hopefully there's a similarity there which your program can recognize, even in compressed format. Now, if you found both of those, you might uncompress the line and do whatever else you want with it. This will make it so that only a small portion of the lines need to be uncompressed, which should dramatically increase the speed. Why not show us what a typical target line looks like when compressed and uncompressed ? StuRat (talk) 12:24, 24 April 2010 (UTC)

Another general comment: Flat files (XML or other) are completely unsuitable to the task of processing such large amounts of data. A relational database would do a far better job, if properly indexed. However, in your case, I assume this isn't an option. StuRat (talk) 12:29, 24 April 2010 (UTC)

The compression (7z) is so efficient because it's an intricate LZ code followed by entropy coding using (I believe) a dynamic Markov model driving a range coder (similar to an arithmetic coder, I think). A string like "Category:... " repeated at various places in the uncompressed text will not be identifiable in the compressed text without actually running the decompression algorithm (it will look different every time, won't be the same length every time, and won't even necessary be on bit boundaries because of the arithmetic codes. To give you an idea, the .bz2 compressed version of the same file is 180+ GB). Also, merely seeing the string "Category: living people" with angle brackets doesn't mean you've actually found those category tags, since the string might occur in the text. You have to actually parse the xml to see that the tag is in the right place in the document structure, to know that it is an actual category tag. The files are in that compressed XML format because the wiki developers release them that way, but yes, populating a database from them might be a good way to make certain kinds of queries easier. I'll give that some thought (I'm not very experienced with rdbms's). Thanks. 69.228.170.24 (talk) 12:40, 24 April 2010 (UTC)

(unindenting) Some thoughts:

1) If the string you search for is different every run, that can be handled, just decompress enough lines to find out how it's compressed this time, then use that as your key.

2) If the string is different at every occurrence during a given run, that that's a more serious problem. I can't think of an easy solution.

3) Occasional false positives are OK; presumably once you uncompress those lines you can filter them out.

4) As for the RDBMS idea, it probably will take longer for the first run, since you have to load all that data into the database, but each subsequent run should be far faster. StuRat (talk) 14:34, 24 April 2010 (UTC)

Expat shouldn't be that slow. I downloaded simplewiki-20100401-pages-meta-history.xml.7z for testing. (7z -so | wc -c) ran at about 280 MiB/s and (7z -so | expat-test-app) ran at about 85 MiB/s, on a Core 2 Duo P8700 running Win7 32-bit. At that rate processing enwiki would take about a day, which isn't too bad.

The test app is written in C and installs dummy start/end/data handlers. I strongly advise you to write your analysis code in C++, since that's usually the language of minimum hassle for programs that need to be extensively optimized.

If you're processing page records in parallel on a multi-core processor, an obvious way to speed things up is to run n simultaneous threads which skip a_i bytes, look for the next occurrence of "</page>\n <page>", and then process until the first occurrence of that string after the a_i+1 byte mark, for i in {0,1,...,n−1}. You could preprocess the input file to split it into appropriately-sized pieces, but you'd have to recompress the pieces, and that could take a very long time.

I think it would be possible to combine 7-Zip decompression and XML parsing for a substantial speedup (basically, lex the output as you go, and then copy lexemes from the sliding dictionary instead of characters). But it would probably be far too large an engineering effort to justify the benefit (a factor-of-3 speedup at best). -- BenRG (talk) 20:01, 24 April 2010 (UTC)

Thanks, 85 mb/sec is WAY faster than other benchmarks I'd seen for expat--maybe something is broken about the wrapper I'm using. OK, I will probably have to write this in C or C++. 69.228.170.24 (talk) 20:33, 24 April 2010 (UTC)

BenRG, when you say dummy start/end/data handlers, you mean you installed callbacks that don't do anything? Or that you didn't pass callbacks at all (I'm not sure if expat allows that, but if it does, it might skip some processing steps in that case). How long does it take to catch the first 10 million expat events and then stop? 85 MiB/sec is around 25-30 cycles/byte on your machine, which is much faster than I've ever heard anyone claim for expat. I will think about your idea of processing page records in parallel without first splitting up the file. The problem is some page records (all the revisions) are very large, like 100's of GB for noticeboard pages that have huge numbers of revisions. Processing individual revisions in parallel on the other hand will require "juggling" since I want to look at differences between revisions. I also have never done any multithreaded programming in C++. I was thinking it would be simpler to just split the file into chunks and then handle the chunks with multiple processes, possibly distributed across several machines. 69.228.170.24 (talk) 03:42, 25 April 2010 (UTC)

If you put the data in a database, it becomes trivial to split the work between multiple processes, even on separate machines. Since the data is constant, you can avoid making the database server or the network a bottleneck by duplicating the database on several machines. IMHO learning SQL and basic RDBMS usage is something every programmer should do at some point. The sooner you bite that bullet, the more productive you'll be in the future. 85.156.90.21 (talk) 06:51, 26 April 2010 (UTC)

I installed callbacks that didn't do anything (except increment a counter). Stopping after 10,000,000 callbacks takes 2.4 seconds. I guess I might have botched my benchmark somehow, but 25 cycles per byte seems entirely plausible to me, since there's not very much that expat needs to do. Most of the time it's skipping bytes looking for the next < character. (Edit to add: I think you're right that splitting the file into chunks is the way to go.) -- BenRG (talk) 08:27, 26 April 2010 (UTC)

removing grub from Windows machine

I have an WinXP-Mandriva dual boot system which starts with grub. I hardly use the Linux and don't want the grub to appear each time I switch on the machine. Can removing the string "c:\grldr="Start GRUB"" from the boot ini prevent the grub from loading? Will XP start on its own once grub is deactivated? --117.204.94.241 (talk) 10:43, 24 April 2010 (UTC)

Are you actually seeing a Grub startup screen first, or only the option to "Start GRUB"? If the latter, removing the line (and making sure the default choice isn't set to the now-missing GRUB line) should suffice.

You can find an example here: Boot.ini#boot.ini

If, however, the first thing you see is the Grub startup screen, you will have to replace the Master Boot Record.

To do this, run the recovery console and enter the command fixmbr

Before doing that, I would recommend getting a Linux live CD and a floppy disk or USB key fob, to store a copy of the current mbr using the dd command - just in case the machine goes belly-up after the fixmbr.

-- 78.43.60.58 (talk) 16:12, 25 April 2010 (UTC)

I was wrong to say it was grub. What I see at the boot is this screen. There are three options. XP on top Mandriva and Mandriva safe mode. After that I again get an OS selector menu, that of XP. black back ground and no graphics. -117.204.86.125 (talk) 11:33, 26 April 2010 (UTC)

Saving only the Google cookie when exiting Firefox

I am using Firefox 3 6 3 and WinXP. I have it set to delete all cookies when the browser window is closed. This means my preferances for Google are lost every time. Is there any way to delete all cookies when Firefox is closed, except the Google cookie. I have looked through the Options menu and not seen a way. Thanks. 78.148.48.230 (talk) 11:52, 24 April 2010 (UTC)

You can do it manually, by copying the cookie to a safe directory, closing Firefox, then copying the cookie back. Of course, Firefox may actually delete the old cookies at startup, in which case you'd need to do the cookie replacement after that. This process could be automated with a batch script. StuRat (talk) 12:12, 24 April 2010 (UTC)

It would be easier to simply re-enter my choices in Google rather than do that, which is what I am trying to avoid having to do every time I start Google. 78.148.48.230 (talk) 12:36, 24 April 2010 (UTC)

"Edit">"Preferences". "Privacy" tab. Set "Firefox will: Use custom settings for history". Turn off "Accept cookies from sites", but click the "Exceptions" button, and add an exception to allow "google.com". Paul (Stansifer) 13:31, 24 April 2010 (UTC)

That will cause the browser to not retain non-google cookies even during the session. I think the desire is to retain all cookies during the session, then delete them all except for some special ones when the browser is closed. I've wanted that too and don't know a simple way. 69.228.170.24 (talk) 13:35, 24 April 2010 (UTC)

Maybe the best solution is to set up Firefox Profiles for your private browsing (and set the privacy settings high, including clear-on-exit). Then, use a different firefox profile (with a different desktop shortcut, for example), to access your non-private profile, which saves your google and other persistent cookie information. Nimur (talk) 14:53, 24 April 2010 (UTC)

Layers in PDFs

I have a PDF which has some graphics over what I want to see. I can see it is a layer, as what is behind it writes to screen but then is covered by the graphics. Is there any way of removing the top layer please? 78.148.48.230 (talk) 11:54, 24 April 2010 (UTC)

Maybe. Open the file in Inkscape, select and ungroup the objects, and then try to delete the top object(s). This may uncover objects underneath (or may not, depending on whether the program that authored the PDF decided to leave, cull, or crop occluded objects). -- Finlay McWalter • Talk 13:01, 24 April 2010 (UTC)

Can any freeware PDF software remove layers or otherwise decompose it? Thanks 89.243.213.182 (talk) 17:23, 24 April 2010 (UTC)

Inkscape is probably as good as any other for this kind of thing. --Mr.98 (talk) 17:13, 25 April 2010 (UTC)

Defining a vague business project

If someone has a vague idea of what they want some business software system to do, what are the techniques or methods used to sharpen up that vaguery into something precise enough so that conventional programming techniques could then be used? Thanks 78.148.48.230 (talk) 12:00, 24 April 2010 (UTC)

1) First, define inputs and outputs. Specifically, what variable types and lengths will be used.

2) Define any forms used to supply the data and the format of any output documents created.

3) Next, create a flowchart of the program.

4) Finally, write pseudo-code.

These steps will lead to the Qs which need to be answered to fully specify the program. StuRat (talk) 12:08, 24 April 2010 (UTC)

Sorry, that is way too far ahead. That is the stage I would want to reach. I should have written business system rather than business software. 78.148.48.230 (talk) 12:40, 24 April 2010 (UTC)

This isn't really a computing reference question; but maybe you could check some "how-to" books on marketing, business, and design. Crossing the Chasm ($9 at Amazon) explores the task of taking a vague high-tech idea and turning it into a marketable product. Your question is worded so vaguely, though, that it's not clear what you are looking for. Business process management might link you to some useful ideas and concepts. And software engineering might help too. Software engineering is quite distinct from computer programming - in general, it is the profession of converting vague conceptual needs into well-designed, implementable features that can be programmed and designed into computer software. Nimur (talk) 15:00, 24 April 2010 (UTC)

An example would be someone who wants to create an online automated system for insuring bicycles. That is their vague nebulous idea: what are the methods or techniques to get it from there to software implementation? I'm not concerned about marketing and so on. Thanks. Update: Thanks for Crossing The Chasm, but I was already aware of the stuff about adopters that the article desribes some years before the book was published, and as I said I'm not enquiring about marketing, just the software and computing parts. 89.243.213.182 (talk) 16:49, 24 April 2010 (UTC)

Then StuRat was on the right track, though he was coming at it from the coder's point of view rather than the customer's (yours). Let's consider this online automated bicycle insurance system, and let's assume it's a Web site. The traditional approach is that you would consider what you want this system to look like and do, from the point of view of each possible user of the system; and once you're done with all the categories of users, and you know what you want it to do for each user, you figure out what "back-end" systems also need to be written. Consider an end user, perhaps a college student. What's the home page of the web site look like? Use a pencil and paper, or Microsoft Powerpoint or a paint utility, to mock up very primitive versions of all the screens. This will force you to figure out at what point you're going to make him sign up for an account, which will force you to figure out what your validation process is going to be, for example. Continue this process for each web page that the college student will interact with. Then consider the system from the point of view of your system administrators; of the underwriters that are the counterparties to the consumers; etc., until you have designed, on paper, all the "interfaces" that each type of user will have to the system. Now you would figure out how the system needs to tie the insurance application to underwriters and get assigned to a pool and do the risk assessments and issue quotes and charge the credit card and all that stuff. Write it all out, in steps. Then at that point you're probably ready to be able to identify what types of talent you need to work with, and have that talent start designing the system at a lower level and start writing code.

Now, I said that was the traditional approach to developing software. Some companies, like some brave video game developers, have been using "agile" development methods like Scrum, in which you don't design it all up front; you write the briefest possible design documents up front, and do "sprints" of one week, designing as you go. This is more appropriate if, as in some (well, probably most) video game development, there is a lot of risk of slippage in development, and/or the objectives are not able to be determined 100% up front — in either case, agile development lets you change course during development with a minimum of wasted development effort. Whether this is appropriate for your system is up to you. Comet Tuttle (talk) 18:02, 24 April 2010 (UTC)

I'm not sure how your comment really relates to the OP's question - but I don't think you understand "scrum" at all - I'm a game developer and I've used that system for several years now. It's certainly not true that you can't design the system up-front with that management technique. Sprints last for three or four weeks during the early stages of the project and shrink to one or two weeks as we close in on a release candidate and are mostly doing bugfix and 'polish'.

It's true that games software companies tend not to do such detailed up-front design - but that's nothing to do with scrum - it's because we're trying to engineer "fun" and that's a tough thing to plan up-front. We need agile approaches that let you change direction in mid-stream because that's what has to happen when something you thought would be fun turns out not to be - or when some odd thing you just tossed into the design as a small feature turns out to be something that play testing discovers to be unexpectedly fun and has to become a much more major game mechanic. However, for the more mechanistic parts of the system (eg How does the disk sub-system stream graphics data from the hard drive? How does the AI sub-system do pathfinding?) - we certainly do design in great detail 'up front' and produce detailed design documents. Then we turn those into "stories" and use scrum to manage the implementation processes.

Over the life of a game, we'll have design "stories", implementation stories, (perhaps documentation stories), play-testing stories, QA stories and bug-fix/polish stories. Sometimes those stories are run consecutively - sometimes in parallel - it depends on the kind of sub-system we're building. We use scrum for programmers - but also for artists, sound designers, story-boarders, etc. The scrum approach is mostly a way for management and system design to interface with the engineers in such a way that 'micromanagement' (which is evil) is kept out of the system and individual engineers are given responsibility to estimate what they can do - and do what they estimate - which gives management more confidence that the system will deliver on time, and give implementers the necessary team spirit and feelings of 'ownership' that are so important to the way they work. The 'agile' part means that if we have to stop implementation and go back to design, we can cleanly do that at the end of the current sprint. But it all happens in a very controlled fashion. SteveBaker (talk) 18:42, 24 April 2010 (UTC)

I'm not sure why you thought my suggestions were "so far out ahead". Let's take the online bicycle insurance project, and break it up into components:

A) Offer a quote.

B) Accept online payments and grant an insurance policy.

C) Provide an online insurance claim form.

D) Provide a "contact us" method for cancellations and other issues.

Now, let's just take on the first part, offering a quote, and apply my suggestions to it:

1) "First, define inputs and outputs. Specifically, what variable types and lengths will be used." You're going to need their name, address, age, gender, number of bicycles, make of bicycles, age of bicycles, condition of bicycles, amount of insurance desired, etc. Why can't this be defined now ?

2) "Define any forms used to supply the data and the format of any output documents created." You probably want one form for info on the person and another for info on the bike(s). As far as output document, you want a printable quote with all the relevant info on it. Why can't this be defined now ?

3) "Next, create a flowchart of the program." In this case, how you calculate the premiums required for a given level of insurance. Again, why wait ?

4) "Finally, write pseudo-code." Why not ? StuRat (talk) 19:28, 24 April 2010 (UTC)

A more traditional process would go something like: 1) meet with business and marketing people and discuss the high-level purpose of the software, including things like user scenarios (use cases). Write this up in a requirements specification (see requirements analysis). 2) Meet with programmers and convert the requirements specification to a functional specification which describes technical features that the program should have, including mockup screen shots and the like. There are a lot of different "process" cults of which Scrum is one, but the basic idea is that you probably want to do one or more iterations of rapid prototyping at around this step. In the case of something like an insurance application (involving private financial info), you probably want to have security review even at this early level, including about making sure your system can pass audits under programs like SAS 70. 3) Going from the functional spec to working code is mostly what programming is about, and there's a lot of flexibility and culture wars about how to do it, but again, follow the standards of the industry you're working in. If it's an insurance app, don't write it like a video game. 69.228.170.24 (talk) 20:18, 24 April 2010 (UTC)

What is Rapport (Internet Explorer)?

Hi, I've seen on Internet Explorer on two different Windows computers that there's this program running in the background called Rapport. Is it a legimate program? I have not noticed it before. Has anyone else seen it running in IE? It's basically this white top half of an arrow in a green box in the far right of the address bar at the top. Chevymontecarlo. 16:36, 24 April 2010 (UTC)

Perhaps the security software from Trusteer? Check the logo on their website. ---— Gadget850 (Ed) ^talk 16:44, 24 April 2010 (UTC)

Ah, maybe someone else in my family got the software from their bank. Thanks. It doesn't seem to be malicious. Chevymontecarlo. 06:05, 25 April 2010 (UTC)

Dolphin emulator

What processors are able to run the Dolphin emulator? Are Pentium 4 and Athlon 64 the only processors that can run Dolphin? --88.148.207.106 (talk) 18:56, 24 April 2010 (UTC)

From the wording of the article, I'm guessing any x86 processor with SSE2 can run the emulator although it's likely some may be too slow. This means most recent x86 processors (recent here meaning released since like 2003 or so) and therefore most recent desktop and laptop computers, more details covered in the SSE2 article. It sounds like it hasn't yet been ported to any other architecture such as the PowerPC [18] Nil Einne (talk) 20:00, 24 April 2010 (UTC)

The requirements listed in the article are minimum requirements. A Core 2 is better than a Pentium 4. -- BenRG (talk) 20:04, 24 April 2010 (UTC)

Turn off/limit drag and drop of links

I regularly try to select a link, but instead of clicking, it either turns purple or gets a dotted box drawn around it. I suspect that the mouse moved slightly while I clicked, and it therefore thinks I'm trying to do a drag and drop. It then refuses to do anything, since that link can't be dragged anywhere:

1) Is my analysis of the problem correct ?

2) How can I prevent this ? Can we either disable the drag and drop feature for links or make it less sensitive, so moving the mouse a single pixel won't trigger that behavior ?

StuRat (talk) 20:51, 24 April 2010 (UTC)

Yes; to sidestep the second question, you can press the escape key to cancel the drag-drop or alternatively drag the link to the address bar (or another tab). 131.111.248.99 (talk) 20:58, 24 April 2010 (UTC)

I assume you are using Windows. In the mouse settings (in the control panel) there is a drag sensitivity setting. Increase it so you have to drag the mouse further to make it be recognized as a drag. I don't have Windows on any of my computers, so I cannot provide the exact location or name of the setting. It should be under Control Panel, Hardware, Mouse, Dragging. -- kainaw™ 21:57, 24 April 2010 (UTC)

There's no "dragging" adjustment under Windows 98 or XP that I can find. StuRat (talk) 00:54, 25 April 2010 (UTC)

I have not used Win 9x for years (last time in 2001), but I cannot recall any such option either. I know you can select the double-click interval, though... --Andreas Rejbrand (talk) 01:10, 25 April 2010 (UTC)

I had a chance to chat with a Windows guy and he said it was part of power toys for Win XP. -- kainaw™ 01:24, 25 April 2010 (UTC)

Thanks, I'll try that on my XP computer. StuRat (talk) 05:21, 25 April 2010 (UTC)

April 25

Impossible hashes

Do the MD5, SHA-1 or SHA-2 hash functions have any strings of the same length as their output which it has been proven they won't output for any input, or will output only for inputs longer than the hash? (A use for such a string would be disabling a user account without deleting it on a system that wasn't designed to make that possible -- just set the "hash of the password" to that value, and then it's safe even if someone breaks the hash function.) NeonMerlin 03:30, 25 April 2010 (UTC)

"*" is traditional in the world of /etc/passwd. I think the easy proof that it works is that it's the wrong length, which doesn't fit your criteria, but does make it clearer what is going on.

Being able to find out anything about the documents that could hash to a particular value is a weakness in a cryptographic hash so the answer is "hopefully not". Skimming the vulnerabilities discussed in our MD5 article, I didn't see any that would allow one to generate an unreachable hash, however. Paul (Stansifer) 04:15, 25 April 2010 (UTC)

There is a trivial probabilistic argument that those strings almost certainly exist, but as Paul Stansifer says, if you can find one you will have in some sense broken the hash. 69.228.170.24 (talk) 07:20, 25 April 2010 (UTC)

Per above, if such a value could be found, it would indicate a weakness in the hash function — It would not be complete. For example, if there are several 160 bit inputs that map to the same SHA-1 output, then there are situations where every output bit does not depend on all input bits. See also Correlation immunity. decltype (talk) 23:08, 25 April 2010 (UTC)

Rainbow table size

I have a password (not on Wikipedia, and I'm not saying where) that's 15 characters long and consists of numbers and lowercase letters. How large would a rainbow table have to be to crack it? NeonMerlin 03:45, 25 April 2010 (UTC)

With all upper/lower case letters and numbers (in ASCII) there are 26+26+10=62 characters per position. Because not all positions are filled, you have to add "null" to make it 63 characters per position. However, null is special in that no non-null character fill follow null. If every possible combination (which obeys the no character after null rule) is used. you have 62^15 combinations with all 15 characters used, 62^14 combinations with 14 characters used, 62^13 with 13 characters used, etc... So, you have 62^(15+14+13+12...) which is 62^120 possibilities (or 1.22e215). Add to that one completely null combination. -- kainaw™ 04:16, 25 April 2010 (UTC)

a^b + a^c isn't a^(b+c). $\sum _{n=0}^{15}62^{n}$ = 781 514 782 079 074 318 856 775 915, which, while well short of 62¹²⁰, is still roughly 2⁸⁹. Orders of magnitude (data) suggests you have little to worry about.—Korath (Talk) 08:33, 25 April 2010 (UTC)

And with just lower-case and letters, you have $\sum _{n=0}^{15}36^{n}$ = 227 390 317 427 040 025 268 341, about 2^77.5. Still infeasible. —Korath (Talk) 08:36, 25 April 2010 (UTC)

That said, a proper rainbow table doesn't need a separate entry for for each combination. —Korath (Talk) 10:30, 25 April 2010 (UTC)

AES and multiple encrypted copies

Does a plaintext encrypted with the Advanced Encryption Standard algorithm become significantly easier to crack if the attacker has multiple encrypted copies, each produced by a different key, but the keys were all generated independently? NeonMerlin 04:45, 25 April 2010 (UTC)

Well, it depends on the encryption mode. If you just mean multiple ECB encryptions of a single block, unless I'm missing something youre fine if the keys are random and AES meets its security specification, of being a pseudorandom permutation. For other modes, who knows. If you want to learn some crypto theory to be able to answer this kind of question yourself, you might like to read Phillip Rogaway and Mihir Bellare's online notes.[19] 69.228.170.24 (talk) 07:23, 25 April 2010 (UTC)

To your original question, no. If the keys are independent, then there's no decreasing level of security with a subsequent encryption. If there was then if I was an attacker I'd just re-encrypt it over and over til it was sufficiently weak. On the other hand, if those keys are related, then now you're talking about a different type of attack. Yes, there are some concerns with it, but I don't know much more beyond that. I think you're probably thinking more about concerns with triple DES, which are slightly similar on face, but fundamentally quite different. If I'm misunderstanding please tell me and I'll try to fix it. Shadowjams (talk) 08:13, 26 April 2010 (UTC)

Weakness of overly long hashes?

It occurred to me tonight that once the hash length exceeds the number of possible plaintexts, increasing the length of the hash function might actually decrease the theoretical security of hashed and salted passwords by making the salt more feasible to guess. If we use a 128-bit hash function to store a password of up to 19 ASCII characters, this makes just under 2^125 hashes possible for a given salt value, meaning that a cracker with a huge precomputed table can eliminate seven eighths of the possible salt values for every known hashed and salted password, even without knowing any plaintext passwords. This means he needs 43 hashes to crack a 128-bit salt. Granted, the table would be 2^5511 bits long (2^(128*43) possible lists of hashes times 128=2^7 bits per hash, neglecting the relatively small amount we'd save by skipping lists that contain duplicate hashes) and take 2^253 iterations of the hash function to generate; but if we stored only 120 bits of the hash then it wouldn't be possible even then. Further, if we switch to a 256-bit hash function, then each known hash narrows the salt space by 2^131, and cracking a 256-bit salt requires only two hashes and a table occupying 2^520 bits. Is my analysis correct? NeonMerlin 05:51, 25 April 2010 (UTC)

tldr, but the idea of cryptography normally is to pick your security parameters so that the attacker has an unfeasible amount of work to do, rather than worrying about attackers with unbounded resources. Those collisions are useless if the attacker can't exploit them within the lifetime of the universe. 69.228.170.24 (talk) 07:29, 25 April 2010 (UTC)

Yeah. Even if your analysis is correct, "only... a table occupying 2^520 bits" is rather a lot. The information capacity of the observable universe is only 2^305 bits. See Orders of magnitude (data). —Korath (Talk) 08:22, 25 April 2010 (UTC)

I was thinking this earlier but screwed up the calculations so confused myself and didn't respond somewhat unnecessary now with the existing responses but in the same vein I guess... Let alone 2^5511 which is so big that neither the Bing or Google calculators handle it (2^1023 being the limit for both). The Windows one does so I know you're discussing 1.18363e+1658 bytes. If you can find something to store and handle that then great. In the mean time...

Of course you have a lot of time to find a solution to your problem since even if you can compute 1 billion iterations of the hash per second, which sounds like an awful lot, you'd still need 4.58663e+59 years (which is 3.299746e+49 times longer then current upper bound estimated age of the universe) to generate your table requiring 2^253 hash iterations.

Nil Einne (talk) 11:29, 25 April 2010 (UTC)

Edit gzipped file without decompressing?

Under what conditions, if any, would it be faster to perform a search-and-replace on a gzipped text file by inspecting and updating the compressed data than by unzipping, performing the search-and-replace and rezipping? NeonMerlin 06:28, 25 April 2010 (UTC)

If decompressing the file would make it too large to fit into memory, and thus require paging or some other method to store the excess data, that may be a point where keeping it compressed is the better strategy. Of course, if it's possible to decompress only a portion at a time, such that it fits into memory, then this changes the equation. StuRat (talk) 06:36, 25 April 2010 (UTC)

What is the application? In a pure sense the answer is "almost never", but zlib lets you insert synchronization points into the compressor output, so that you can (for example) edit blocks in the middle of it. This has a slight cost in compressed output size. 69.228.170.24 (talk) 07:32, 25 April 2010 (UTC)

That's a good point about decreasing the efficiency of the compression. If the replace string is the same length as the original (specifically if this is true of the compressed versions), then that should work better. StuRat (talk) 07:39, 25 April 2010 (UTC)

Geographical Information software: OS OpenData

Hello. Can anyone recommend me a free (preferably open-source) and simple GIS which will be capable of processing all the UK government datasets that have just been released? Thanks! ╟─TreasuryTag►person of reasonable firmness─╢ 10:40, 25 April 2010 (UTC)

Try Data.gov.uk. Kittybrewster ☎ 11:16, 25 April 2010 (UTC)

Er—no. Was my query poorly-worded? I'm looking for a Geographical Information System: software with which to load the date released by Ordnance Survey. ╟─TreasuryTag►voice vote─╢ 12:10, 25 April 2010 (UTC)

I expect you have already looked at Comparison of geographic information systems software, including the links at the end of the page. 89.243.216.99 (talk) 12:49, 25 April 2010 (UTC)

Yes, I have, but it's not sufficiently clear to indicate which software is able to process which formats of data :( ╟─TreasuryTag►First Secretary of State─╢ 13:45, 25 April 2010 (UTC)

Quantum GIS should be able to open most, if not all of the formats listed. I know it can do ESRI shapefiles and (I think) TIFF images, plus any software should be able to import ASCII text files. It isn't the most user-friendly program (the manual for the latest version is 270 pages) but I think it's easier to use than most other GIS programs under active development -- plus it's free and open-source. I would be happy to respond to QGIS questions through e-mail, if some come up while you're working. Xenon54 / talk / 14:06, 25 April 2010 (UTC)

A problem with Facebook

Why do my friends who have type 1700 friends Facebook tell me that they only have 400 and not see all the other 1300? If by the "show all", tells me that the person has only 400 friends e. .. but it is not so and more than 400 I do not display them ... Makes me with all my friends. For example, a friend of mine who has 287 friends I have only displayed 285. I have a friend who has 490 friends. I clicked on "490 friends" of his board or the "show all" of its board, but Facebook has shown me only its first 398 friends and all others not as well not exist. Perhaps that might be Facebook, with the new change, it makes that you can see only a limited number of friends of your friends because if not, with new subscriptions to facebook, the server becomes overloaded.? What do you think? Let me know. Hello and thanks in advance. —Preceding unsigned comment added by Plantigrados (talk • contribs) 16:51, 25 April 2010 (UTC)

PHP

Resolved

Say I have a text file with the data "1" "2" "3" etc all on new lines. How would I call this data to display using php, so that it would display something like:

<font color='red'>1</font><br>
<font color='red'>2</font><br>
<font color='red'>3</font><br>

and if I changed the data in the text file to say "1" "2" "hello" it would display something like:

<font color='red'>1</font><br>
<font color='red'>2</font><br>
<font color='red'>hello</font><br>

To clarify, the text file itself would look like:

1
2
3

Thank you 82.43.89.71 (talk) 16:52, 25 April 2010 (UTC)

There are many ways to do this. Here is an easy one that is pretty flexible:

<?php
ini_set('auto_detect_line_endings', true); 
$lines = file($filename);
foreach($lines as $line) {
    echo "<font color='red'>$line</font><br>\n";
}
?>

That loads the contents of $filename into an array named $lines, then just goes through each line in the array and outputs it in your preferred formatting. The first line just tries to compensate for the fact that different file formats use different line endings (and will make your life effortlessly easier when reading from text files in this way). --Mr.98 (talk) 17:11, 25 April 2010 (UTC)

Squee!! Thank you :D 82.43.89.71 (talk) 17:30, 25 April 2010 (UTC)

Computer math operations

How does a computer perform addition and other operations. I assume it's done by the ALU, but I don't know how it physically works. I'd guess that each number is transformed into it's binary equivalent, which you can represent by having a switch on or off, but (even if this was right), I don't know what happens next. Would calling the computer to do an arithmetic operation be similar to calling a program, in that it goes into the memory location, etc.?

Also, would stuff like integration be done by the ALU or a program you write? Could you just point me in the broad direction for how someone would write a program for integration? Do I have to convert the function into Taylor series?

Thanks! 66.133.196.152 (talk) 17:51, 25 April 2010 (UTC)

For an explanation of the how hardware performs the simplest arithmetic operation, addition, see Adder (electronics). As for where the two numbers to be added are located, some computers require that they first be moved from memory into a register, while other computers allow addition directly from memory locations.

As for numerical integration, we have an article about that. There are many methods, but I would be very surprised if there is any ALU or CPU that can do integration directly; a program would be needed. Jc3s5h (talk) 18:20, 25 April 2010 (UTC)

(edit conflict)If you're talking about integer arithmetic, addition is done by a circuit in the ALU, the adder. Negation is done by taking the two's compliment. Subtraction is done (often) by negation followed by addition. Integer multiplication is performed by a number of schemes described at binary multiplier and linked articles; likewise division (digital) describes how division is done. As shifting is very easy, many multiplication and division implmentations have shortcuts that try to do some or all of the work by shifting, as applicable; similarly as division and multiplication by small integers is common (you'll find many more programs that ask for division by 3 than by 197) many processors have special shortcuts for a select few integers (that are implemented using the algorithms described above, but with some of the steps hardwired). Most modern cpus had ADD, SUB, MULT, DIV, and NEG instructions. For non-integer operations, floating point operations are implemented in most CPU's "floating point unit", a part of the chip that does arithmetic ops for floating point numbers. Some applications (such as number theory and cryptography) need accurate handling of very large integers (which overflows the CPU's ordinary arithmetic unit, and for which the FPU isn't sufficiently accurate); these use fixed-point arithmetic schemes; unlike the others fp arithmetic is mostly done in software. More advanced operations, like logarithms, exponents, and the values of functions like sine, are done using software that builts on the elements described above (usually floating-point); the specific wikipedia article for a given function will often describe the computer algorithm that calculates it - see Trigonometric functions#Computation for example. SOmetimes these are mathematical expansions like Maclaurin series, but very often they'll use special algorithms that take into account the computational characteristics (and the need for accuracy, or not) of the computer and the desired application. -- Finlay McWalter • Talk 18:28, 25 April 2010 (UTC)

High-level summary: numbers are stored as a binary representation all the time. A rather large proportion of the primitive CPU instructions are the four basic math instructions (things like "add two floating point numbers", "divide two integers", etc.). The logic gates that accomplish these instructions look a great deal like elementary school arithmetic, but in base 2 (this makes some things much simpler: the 100-element multiplication table we're used to now has only 4 elements). In many cases, you'd be able to match up individual wires to individual digits in the intermediate results that base-2 schoolchildren would get. (However, in order to go as fast as possible, the design will usually turn out to be more complicated than that.) Paul (Stansifer) 04:26, 26 April 2010 (UTC)

Besides numerical integration there is also symbolic integration (a not very helpful article right now). Symbolic integration means your program accepts a formula like f(x)=3x² and integrates it to give the formula x³+C. This can be done with pencil-and-paper methods or with fancy algebra (Risch algorithm) or some combination of both. 69.228.170.24 (talk) 10:00, 26 April 2010 (UTC)

April 26

ripping

whats a good free thing to rip youtube vids —Preceding unsigned comment added by Tom12350 (talk • contribs) 06:37, 26 April 2010 (UTC)

Check these out. BTW, the question above was asked by Tom12350 (talk). 24.189.90.68 (talk) 09:03, 26 April 2010 (UTC)

I have used keepvid.com. Graeme Bartlett (talk) 09:13, 26 April 2010 (UTC)

keepvid doesn't work all the time. I use freestudio's suite of programs that includes a youtube downloader. -- Buffered Input Output 12:54, 26 April 2010 (UTC)

Bluetooth headset and skype

I'm using a bluetooth earpiece headset with skype, but I'm having troubles. My dongle is by a (Japanese?) company called PCi (BT-MicroEDR2X) and the headset is a Logicet LBT somethingorother, and pairing works and I can use it with skype, but if I turn off the headset and turn it back on, it doesn't work anymore, even though it says it should be. If I delete the device, repair and reboot it, it works again, but every time I turn it off and on again it stops working. I'm a bit new to bluetooth, does this happen a lot? 210.254.117.185 (talk) 12:05, 26 April 2010 (UTC)

php question

In php, what might "$line[$j]" do? 82.43.89.71 (talk) 14:54, 26 April 2010 (UTC)

That is syntax for accessing an array. Here is the PHP Array manual. Such notation seems to indicate that somebody has previously stored several lines (maybe text, but it could be anything) and indexed with a counting variable. Nimur (talk) 16:08, 26 April 2010 (UTC)

Deleting entry history in Safari

Hi, when I type an edit description in the bar in WP it shows up past edit descriptions that I have entered. How can I remove these? I hope you understand my question, I don't think I worded it very well :D Chevymontecarlo. 17:19, 26 April 2010 (UTC)

Question

My work place blocks many websites from access. Is there a way I can connect to my home computer from work, and use its internet which is not restricted? I am very uninformed with computers, could there be a simple program that is not complicated?