Wikipedia:Reference desk/Computing

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July 6[edit]

What is Bit capacity of analog tape ?[edit]

As I understand bits is for digital information.OsmanRF34 (talk) 21:33, 6 July 2014 (UTC)

Tape stores digital data in an analog format. See Magnetic tape data storage. --  Gadget850 talk 21:51, 6 July 2014 (UTC)
Not very helpful.OsmanRF34 (talk) 13:00, 7 July 2014 (UTC)
Magnetic tapes do not have a well-defined bit capacity. The capacity depends on the details of the method used to store data, and the capacity that can be obtained with a particular method depends on the detailed structure of the tape. Looie496 (talk) 03:05, 7 July 2014 (UTC)
Recent news in the analogue tape world. Vespine (talk)
But they don't have a well-defined bit capacity because they are analog? And there is no thing like an "analog bit"? I'd check Units of information but the article has no reference to an analog bit type of unit. The question is more about measuring amount of analog information than about tape.OsmanRF34 (talk) 13:00, 7 July 2014 (UTC)
The conceptual difference between an analog signal and discrete signal.
This question cannot really be answered without further assumptions, which is why you are getting some finicky non-answers. But I can maybe help you out with some ideas of ways to compare information stored, and some links. So, maybe you're thinking about audio cassettes, which commonly held 30 minutes of music on each side, but some could hold up to 60 minutes of audio on each side. This audio is represented as an analog signal, and it is pretty much directly read by the player and sent to the speaker without much processing. In comparison, a compact disc holds about 80 minutes of audio, but since it is digitally encoded, the actual amount of audio it holds will depend on the sample rate. The point is, if we only focus on use for playing/storing audio, some tapes hold about as much as a CD. Sample rate is a key concept when converting to/from analog/digital. Increasing the sample rate makes the digital signal "closer" to the analog, but it also takes up more space.
There isn't really anything like an analog bit, bit literally means a binary digit. If we want to encode an analog signal into a digital medium, we might end up with something like this image from discrete-time signal. Think of the smooth curve as analogous to what is contained on a tape or on a groove in a vinyl record, and the red "step" line as analogous to what is contained on a CD (NB this is only an analogy). Basically, an analog signal is conceptually continuous, while digital signals are conceptually discrete. So, if you fix specific types of analog to digital and digital to analog conversion, and tape specification, you can come up with a statement like "this tape can hold roughly X bits of data" -- but unless you specify all those things the question is ill posed.
Now, if you're really interested in how information is measured in an analog domain, one way that can be quantified is by Bandwidth_(signal_processing) (Note that though the term is commonly used for things like internet speed, it is inherently an analog concept), which measures how "wide" the signal is in the frequency domain. But beware of casually skimming topics in information theory, the Shannon's notion of information is that a recorded one-hour sample of white noise has more "information" in it than a recording (1 hr) of Principia Mathematica -- so keep in mind that information has many different definitions, and each is useful for different purposes.
Finally, if pressed to answer "how many bits are in this analog signal?", Infinite is a fairly defensible answer, because we'd (in general) need the entire infinite Fourier series to faithfully represent it digitally... Does any of that help? SemanticMantis (talk) 15:50, 7 July 2014 (UTC)
I disagree with "infinite". First, current technology will limit how many bits can be encoded on a given analog tape and retrieved reliably. If you tried to go beyond that number, single bit errors would start cropping up, and eventually the information would so corrupt as to be useless. But, assuming we ignore technology limits, even in a theoretical sense, there would still be some limit, due to quantum randomness.
It might help to use writing on paper as an analogy. You can encode digital info that way, by using the pencil to make a dot to represent each bit (that would be a 1 and the absence of a dot there would be a 0). How small and closely together you can make the dots then becomes the limit on the number of bits that can be stored that way. Theoretically, the limit would be one carbon atom (or the lack thereof) per bit. However, practical limits may kick in far sooner, as single atoms of carbon are probably already there, and those you deposit could evaporate away. And devices which could deposit and detect a single carbon atom, while they may exist, are extremely expensive. So, encoding that much digital data just isn't realistic. StuRat (talk) 16:24, 7 July 2014 (UTC)
I was not talking about encoding bits onto tape, I'm talking about representing an an analog signal with bits. And I said "infinite" was a defensible answer, not the only correct answer. I don't care to discuss engineering issues here, but you've prompted me to give to defend the claim. Conceptually, analog signals of a given length form an infinite dimensional space. If you want to think of sound waves in the air or grooves in vinyl as discrete signals due to physics at the molecular level, that's your prerogative -- but for most purposes and applications scientists and engineers consider them to be analog and continuous. You can call it a Mathematical_model if you like, but it's a damn good one. For specific examples of infinite dimensional spaces of analog signals, L2 is a space of fairly "nice" signals that form a Hilbert space. Even if you restrict to the "nicer" class infinitely smooth analytic functions, you still have an infinite dimensional space. This is in some ways similar to the the question, "How many positions are available on a slide trombone?" The answers "seven", "many", and "infinite" are all defensible. It all depends on who's asking and why. I gave the more formal analytic approach, because it seemed closest to the OP's question about the theory of how information is quantified in the analog domain. SemanticMantis (talk) 17:02, 7 July 2014 (UTC)
Gross bit rate describes some of the historic data rates, although not specifically for audio tape. StuRat (talk) 16:38, 7 July 2014 (UTC)
This may be of relevance: Nyquist rate, Bandlimiting, Nyquist–Shannon sampling theorem, [1], [2]. To be perfectly honest, though, I'm not the best at DSP stuff, so it would probably be better if someone else elaborated here for details.Phoenixia1177 (talk) 03:58, 8 July 2014 (UTC)
Ah, good! I forgot about N-S sampling theorem. That is highly relevant here, but the math might be a bit advanced for some. Basically, the theorem says that finitely many samples can give perfect fidelity in an analog-to-digital scheme, but only if the analog part is band limited. This fits in with my comment above that "we'd (in general) need the entire infinite Fourier series to faithfully represent [the analog signal]." -- If you know certain things about the signal, then sometimes we can achieve non-lossy A-to-D conversion. SemanticMantis (talk) 17:04, 8 July 2014 (UTC)

July 7[edit]


How can I play mp3 songs on an ipad mini. thank you. (talk) 03:29, 7 July 2014 (UTC)

That depends. Are they already on the ipad mini? You should see them in your Music/iTunes app. If not, you'll need to download them from online or another computer/device. Apple Support for iPad and iTunes [3] is a good place to start. El duderino (abides) 21:18, 11 July 2014 (UTC)

Middle mouse button.[edit]

I'm running windows 7 with a Microsoft 2 button + wheel mouse. I am very happy with it except that when I scroll the wheel, I almost always end up clicking it and that often causes a program to start doing something (often slow continuous scrolling!).

Is there any way to disable the wheel click but to retain the wheel scrolling? -- SGBailey (talk) 10:41, 7 July 2014 (UTC)

In control panel under "mouse" you should be able to configure the buttons. But perhaps a less sensitive mouse would be good to consider sometime down the line. You may find you'll miss that middle mouse button eventually. Mingmingla (talk) 17:29, 7 July 2014 (UTC)
I'd say, try a different mouse. A quality mouse comes with a wheel that is both easy to scroll and fairly resistant to pressure(so you don't end up clicking when trying to scroll).
Some cheap mice are quite hard to scroll, which means you have to push the wheel (*click* – damn!), or don't have a constant pressure threshold (*push* – huh?) for the wheel button. The price differences are not huge, but around $10, there are very few mice without any flaws. Other bugs include weak optical logic – ball-mice used to "jam" when dirty and didn't move along one of the coordinate axes, while weak optical mice tend to wander off into any direction, or simply disappear and reappear in one of the corners.
However, there are quite decent mice around $20 (so no great deal if you don't go through mice like crazy) and in the long run, you might be better off with a different mouse. Avoid devices made in China if you have the choice. - ¡Ouch! (hurt me / more pain) 08:11, 8 July 2014 (UTC)
I was with you until the last sentence. That is a joke, right? Anyways, I've had plenty of mice (Warcraft III seems to wear down the cable, so they all die of contact issues in the cable). I now have a cheap optical Logitech that has held up for some years (made in China, of course - what isn't?). --Stephan Schulz (talk) 11:23, 8 July 2014 (UTC)
I had the feeling I went through two Chinese mice for one Taiwanese. OTOH, the latest one is Chinese and not TOO shabby. It's getting harder each day to find non-Chinese hardware too; if they're catching up, they might be worth my money in a year or two. Right now, I prefer to use one $20 mouse to two $10 ones. Less getting used to different hardware on my part, and more things actually getting done. - ¡Ouch! (hurt me / more pain) 15:18, 8 July 2014 (UTC)

It is a decent mouse (Microsoft). I can't find any settings in the control panel to do this. I can do things to the left button or the right button or to the wheel scrolling size, but not to the wheel button. Anyway thanks, I'll just continue suffering. -- SGBailey (talk) 11:33, 8 July 2014 (UTC)

@SGBailey: There may be third party software that provides additional options for mouse control. E.g. I use this software [4] to get more out of my touchpad on OSX. Best I windows options I could find at a short search was this [5]. SemanticMantis (talk) 17:20, 8 July 2014 (UTC)
Don't assume it's a quality mouse because it says Microsoft on it. If you look at the box or label, I bet you'll find it's just cheap crap made in China. StuRat (talk) 00:14, 9 July 2014 (UTC)
I feel like Emmett Brown right now for starting the "Made in China" topic. ("I must be the electronics, Marty. Look a this, it's 'Made in Japan', no wonder it's fried.")
Maybe the savings in manufacturing actually go into some better components. There's still not much use in a superior image sensor if every other one ends up misaligned. :(
Let's say I had a lot of bad luck with China, and I know a victim (not dead or hurt, but it was quite expensive) of a PSU fire. I don't have anything WP:RS-like about mice, or why so many optical mice tend to "teleport", though. - ¡Ouch! (hurt me / more pain) 05:57, 9 July 2014 (UTC)

section numbering in latex[edit]

I m writing a thesis in latex using texstudio.But first chapter section start numbering as 0.1,0.2,.... so on up to 0.10 but my problem is for next chapters .chapter 2 section numbering starts from 0.11,0.12,... but i want to start it as 1.1,1.2,... — Preceding unsigned comment added by (talk) 19:24, 7 July 2014 (UTC)

This can happen when the "counter" in LaTeX gets screwed up with conflicting packages and class files. You can fix this manually with the \setcounter command, and you can change the increment behavior using the variables 'thechapter' 'thesection', etc. Some similar questions and answers here [6] [7] [8]. You could also post your question at one of the first two links for more help. If you want more help here or there, it will be much easier if you can post a minimal working example of the .tex file. SemanticMantis (talk) 19:43, 7 July 2014 (UTC)
More typically, this happens if the wrong structuring elements for the document class are used. Book and report classes usually have "chapter" as the highest level element, then sections. If you use a \section{} without an enclosing \chapter{}, the first section is by default section 1 of chapter 0. So either use article class, or start with chapters. --Stephan Schulz (talk) 22:05, 7 July 2014 (UTC)
Is it weird that it starts with 0.1? Wouldn't 0.0 or the more traditional 1.1 make more sense? (talk) 09:21, 10 July 2014 (UTC)
Well, "more sense" depends on your outlook. But from an implementation point of view, whenever you have a new \chapter{}, the chapter counter is increased by one, and the section counter is reset. The first section of the first chapter is 1.1. So if you are "before" the first chapter, the chapter counter is 0. --Stephan Schulz (talk) 10:22, 10 July 2014 (UTC)

July 8[edit]

Why is Google finding an old Wikipedia article?[edit]

Maybe it's different for you, but when I Google (no quotes) "HM patient" or "HM disorder", I get the current Henry Molaison page first, with the full name highlighted as a synonym, along with the other words. When I try "HM memory", I get HM, which is currently a disambig page, but used to be Molaison's article title, and is still treated as such. The word "memory" isn't highlighted in the snippet, but "H.M." is.

Does the term "memory" have a special back-in-time function on Google? Or what else might be happening here? InedibleHulk (talk) 03:04, July 8, 2014 (UTC)

"HM 1926" also finds the old article, with "1926" highlighted, while "HM 1926 memory" finds the new one, with all terms highlighted. So I guess it isn't a special "memory" keyword doing this. InedibleHulk (talk) 03:10, July 8, 2014 (UTC)

Remember that Google locates pages not just by their content but also by the terms people use when linking to them. These are likely to be similar for both locations where the article has been, so you get both locations in the search result. In addition, different pages may stay different lengths of time in their caches, producing this sort of anomaly. -- (talk) 05:24, 8 July 2014 (UTC)
  • Google is weird like that. I don't use my real name on my user page, but searching for it in Google brings back User:Crisco 1492 as the first link. — Crisco 1492 (talk) 05:56, 8 July 2014 (UTC)
That's a bit scary. A search for "bun" finds me blood urea nitrogen first and bun...somewhere beyond the first seven pages, probably. No Bun (hairstyle), either. I'll accept "Google is weird" as reason enough, I think. InedibleHulk (talk) 06:19, July 8, 2014 (UTC)
Google uses locale for ordering pages. If people in your IP locale do medical searches often, your results will lean towards medical terms, such as a BUN lab. — Preceding unsigned comment added by (talk) 11:31, 8 July 2014 (UTC)
  • Probably explains why my Wikipedia profile comes up, as I do a lot of Wikipedia-related searches. — Crisco 1492 (talk) 11:34, 8 July 2014 (UTC)
Yes, but the question remains how it put your WP searches together with your real name. It's not, from what I see, on your user page. Dismas|(talk) 14:21, 8 July 2014 (UTC)
There's several sites (of course, I can't think of any right now) that prowl the web and aggregate accounts with the same username and data - for example, for me, if I had a blog that listed my Phoenixia1177 email on it, it might pool that with my wikipedia username. Once all that is aggregated, it then offers up usernames, site memberships, addresses, phone numbers, etc. indexed for searching for paying members. Essentially, they stalk people online for you - but, some of this data is given for free, like what real names correspond to Twitter/FaceBook/etc. Perhaps Google does something related; or makes the association from such sites when it scans them. --I have no sources, but I've stumbled across my own info before by searching various user names I use; it's actually a little scary (sadly, not shocking) that there are automated systems out there doing all that right now...Phoenixia1177 (talk) 17:10, 8 July 2014 (UTC)
Right, which is why some security-conscious internet users use different pseudonyms for each site. I myself was considering using my WP moniker on a different site. I decided against it. Then I wondered if even "franticmantis" would be close enough for cross-contamination. But now that handle is linked to this one, so I can't use that either o.O SemanticMantis (talk) 17:15, 8 July 2014 (UTC)
  • Oh, I know exactly how my real name is linked to my user name in Google's databases. I take credit for my photography and digital restorations under my real name, and that has appeared on the MP. I'm just somewhat surprised that Google puts my Wikipedia page before other instances of my name (my Flickr feed, for instance, isn't even on the first three pages) — Crisco 1492 (talk) 01:04, 9 July 2014 (UTC)
Google simply loves Wikipedia, from A* search algorithm to Z (1969 film). Maybe for the best. When I search "potato" and exclude Wikipedia, my mind is blown. Potatoes shouldn't do that. InedibleHulk (talk) 01:23, July 9, 2014 (UTC)
The suggestion by 209 can't be correct. I doubt that InedibleHulk and I are in the same IP locale yet a search for bun gets the same results as him. For the HM searches I get the same results except that the first link for "HM memory" says it is HM on Wikipedia but when clicked on goes directly to Henry Molaison. It's easy enough to put user names with real life names if, like me, you use the same user name on different sites. My real life name is in the first hit on the second page of Google results (it's on my user page sort of). CBWeather, Talk, Seal meat for supper? 00:49, 9 July 2014 (UTC)
The HM thing is the same for me, too. Goes to Molaison with no redirection. Hovering over the link shows the URL is right, just the title is wrong. InedibleHulk (talk) 01:03, July 9, 2014 (UTC)

Running a different OS (Linux? Ubuntu?) on a 10 year old laptop[edit]

I have a laptop that is about 10 years old and is currently running Windows XP. It has nothing of value saved on the hard disk. I find that XP is very glitchy and would like to completely reinstall it on the laptop. However, it seems pointless installing XP on a laptop in this day and age since it is so outdated. I also do not want to buy a new version of Windows. I would quite like to just install an OpenSource operating system - the two I have heard of are Linux and Ubuntu, but I am sure there are many others available. Firstly, I have only ever used Windows. How challenging is it for someone (who is not very computer adept) to learn how to run a new OS on a computer? Secondly, will I encounter any hardware problems running a different OS on a computer that ran XP? Thirdly, will I have any problems getting software to run on the new OS? All I will really need is OpenOffice, something to play music and film, and the Open Source version of Photoshop (Gimp?). Also, do you have any other advice for me as to how I go about doing this? Hella New Thing (talk) 14:05, 8 July 2014 (UTC)

Ubuntu is one flavour of Linux. It's the one I would normally recommend to beginners, but newer versions don't seem to universally play well with old and slow graphic cards. You can try e.g. CentOS or Fedora instead - or try them all (they boot from USB sticks for tryout) and stick with the one you like best. All will have OpenOffice (or LibreOffice), and support for playing and manipulating most modern media. As for the difficulty: From my controlled study of 70 year old non-computer-users, the initial barrier automatically wears down in a week or two;-). --Stephan Schulz (talk) 14:18, 8 July 2014 (UTC)
Ubuntu is probably too much for that machine, particularly for the graphical reasons you mention. Ubuntu variant Xubuntu has lower requirements, and Lubuntu is lighter still. I'd be pretty confident of Lubuntu working well on any machine beefy enough to run XP, and Xubuntu may work okay, depending on the machine's specifications. I doubt the machine will be so puny that it can't run these; if it were, there's a lower-tier of Linux distributions with a fanatical concentration on running on old, underpowered machines - things like Puppy Linux. -- Finlay McWalterTalk 21:02, 8 July 2014 (UTC)
VLC_media_player is your go-to media player, and I might recommend Inkscape in addition to Gimp. Whatever *nix you install, make sure you get a feel for the package manager, e.g. Ubuntu uses apt-get. This will make it much easier to install new software. Many of the best open source software packages are hosted on Sourceforge, you can browse through there to find all kinds of fun free stuff. As for ease of learning, I'm not sure if e.g. apt-get has a GUI front end on the Ubuntu distributions, but a little time invested in learning a command line interface like the Bash shell will probably pay off, though this is probably not strictly necessary for normal email/web/media use. SemanticMantis (talk) 17:11, 8 July 2014 (UTC)
Ubuntu's current package-management GUI application is Ubuntu Software Center (which looks and works like a somewhat basic app-store); other Ubuntu variants still use Synaptic (but USC works on Xubuntu and Lubuntu, and can be installed with Synaptic or apt-get). -- Finlay McWalterTalk 21:56, 8 July 2014 (UTC)

Challenging browser problem[edit]

I want to have continuous vertical scrolling. Sometimes at Flickr or Facebook for example, when you go through a big list with hundreds or 1000 and more items (May it be images or People's lists), The window shows only a tiny bit every time you got to the end of the scroll bar. what I want to have is some kind of an automatic command that when i turn it on, The browser will automatically scroll down till the end of the items list (I don't care how much time it's gonna take)... Do you guys know any way I could achieve this goal? (I have no knowledge in Script writing). thanks. Ben-Natan (talk) 23:30, 8 July 2014 (UTC)

Although not a script, you can hold down the End key on the keyboard to keep jumping to the bottom of the page and loading new content. When you see all the content is loaded, you can let go and press the Home key to jump back to the top. Does this fit what you want? --Bavi H (talk) 00:16, 9 July 2014 (UTC)
I'm guessing he wants it to smoothly scroll past everything, so he can find what he's looking for quickly, while your method would jump past lots of stuff. StuRat (talk) 00:19, 9 July 2014 (UTC)
In my method, the first step (holding down the End key) is just so you can load everything, you aren't able to read comfortably in this step. Once you see the page has reached its true end and no longer loads new content, the second step is to press the Home key to jump back to the beginning. Now you're at the top of the fully loaded page, you can read and scroll at your own pace and the scrollbar will consistently indicate your true position in the fully loaded page. --Bavi H (talk) 00:20, 10 July 2014 (UTC)
That should work, but on a huge web page on a slow browser, that could take several minutes before you can read anything. StuRat (talk) 00:41, 10 July 2014 (UTC)
True, but Ben-Natan said "I don't care how much time it's gonna take", so I think it might fit what he wants. --Bavi H (talk) 02:18, 11 July 2014 (UTC)
Before the middle mouse button created new tabs, it usually started a continuous scroll mode. I know that IE6 did. You could click the middle mouse button and then move the mouse up or down. This should do the trick, without keeping a key or button pressed. (I didn't find that feature useful but it was there. No clue if newer browsers can do it, but it could be a compatibility setting. I wouldn't suggest IE6 for long lists (or long articles for that matter); it performs like O(N^2) with these when the competitors are closer to O(N log N).) - ¡Ouch! (hurt me / more pain) 06:16, 9 July 2014 (UTC)
With due respect, you should not use the algorithmic complexity notation to express your frustration with a slow user interface. In actual fact, correct compliance with the HTML document object model requires algorithms that are much worse than O(n2) for an HTML document with n nodes. A fairly recent archived mailing on the World Wide Web Consortium's CSS list estimates that the algorithmic complexity for constraint satisfaction of the DOM for an n-node webpage is exponential in n : O( Dn ) for D layout constraints and n document nodes. Modern web browsers use heuristics to parse the document tree, essentially violating the exact to-the-letter specifications. Arguably, older browsers are more standards-compliant than newer ones! But in reality, the performance of the user interface of your browser probably is more limited by implementation details - like choice of graphics library, or efficiency of memory-use - than by theoretical limits imposed by the algorithmic complexity of the layout engine.
Here's a recent blog, which was featured in last month's Planet Webkit front page on : Automatic Grid Placement algorithms with CSS, which is written at a level that most programmers can follow (without too many confounding implementation and theory details). There is much discussion of spec-compliance, and several links to the W3's canonical DOM definitions.
Here's a more theoretical guide to constraint programming concepts, Constraint Satisfaction, focusing more on the math (and with no emphasis on its application to solving the HTML or webpage layout problem). It's a great website to help familiarize yourself with the fundamentals.
If you enjoy spending a few hours reading about layout algorithms, you might as well read The Java Swing Architecture and the extensive links from that page. Swing, its layout, look-and-feel, and abstract windowing and UI backing layers, were designed to be very algorithmically efficient, especially compared to the HTML DOM. Here's how layout management worked, with visual examples. Yet, many people will anecdotally tell you that Java user interfaces are "sluggish" - evidence again that the user experience and latency is probably more limited by practical implementation details than by actual algorithmic complexity. It is unfortunate that on many platforms, Java's windowing and UI were backed by software-emulation instead of high-performance native libraries; a very well-designed and efficient technology was in many ways lamed by its implementation-details - particularly on important operating systems like Windows.
Nimur (talk) 06:33, 9 July 2014 (UTC)
Middle clicking on anything that's not a link in a webpage will still give the "move mouse to scroll" behaviour (at least in Chrome and IE9, which are all I have access to at work). MChesterMC (talk) 08:26, 9 July 2014 (UTC)

Web page loading[edit]

I've never been happy with the way web pages load. There are several problems:

1) They don't always load from the top down. So, you can't just start reading it as the rest loads.
2) Pics don't load at their full size initially. I'd like a frame to appear at the proper size, then fill in the detail later. This would prevent the text from jumping around as pics above the text are resized.
3) They often load a limited amount, then wait for you to get to the bottom, and possibly hit a page forward button, to load the next page. This leads to a lag while you wait for the next page to load. I realize they probably can't load all the pages, but loading the next page in background, after the current page is loaded, would make sense.
4) Scrolling often doesn't work properly while it's loading a page. Either it doesn't scroll at all or scrolls in jumps and starts. They need to allocate more resources to scrolling so this doesn't happen.
5) Video often starts without me clicking a play button. This is annoying and wastes valuable resources.

I realize that much of this could be fixed by faster computers and internet connections, but that's no excuse to do things in an inefficient way. So, is there any browser which will load web pages as I've outlined above ? StuRat (talk) 16:55, 9 July 2014 (UTC)

WOW, lot's of information was given... any humble summing of a few words --- what exactly should one do? (please don't explain me of computer sciences, I am not familiar with this field). Ben-Natan (talk) 06:00, 10 July 2014 (UTC)
StuRat, what kind of connection do you have?! It sounds almost as if you are using something below 56k speed. Also, what kind of computer are you using?
1) If it was plaintext, I might understand, but it's HTML, which needs to load the entire page to discover how it's going to render it completely.
2) Pictures should be loading with their correct size even if they aren't completely loaded yet. What browser are you using?
3) Resources. Why load something when you don't know if the user is going to look at it?
4) Shouldn't happen. Again, what browser?
5) I can agree here, except for cases like YouTube in which you're highly likely to want to watch the video whose page you just loaded.
Thanks. -- (talk) 17:18, 10 July 2014 (UTC)
3) Well, if I just read pages 1-5, it's a reasonable bet I'm about to read page 6, isn't it ? I can possibly see not pre-loading page 2, since most people who look at page 1 of a document may never go on to page 2. It also somewhat depends on how sequential the data is, though. StuRat (talk) 14:10, 11 July 2014 (UTC)
4) I use Firefox on my old Windows 98 PCs, and Chrome on my Windows 7 PCs. I also have Opera and IE, but tend not to use them much. StuRat (talk) 14:07, 11 July 2014 (UTC)
Just some qualifying points:
2) Pictures: this is dependent on the person who coded the site. If they have not correctly specified the size of the image in their code, the browser cannot correctly size the placeholder until the image has been loaded. Well-written sites should not have this problem.
3) Loading ahead: many browsers do preload the next page etc (e.g. Chrome). You can sometimes turn this setting on and off.
Noiratsi (talk) 17:32, 10 July 2014 (UTC)
Where do you turn on the pre-load feature in Chrome ? StuRat (talk) 14:07, 11 July 2014 (UTC)

July 9[edit]

Downloading and saving material from the internet onto a home desktop computer[edit]

I have a question about computers. I am not that computer-savvy or tech-savvy, so please keep that in mind when replying. Thanks. If I go to a website and see a photo that I like, I can download (save) that photo onto my personal home computer (desktop). So, if that photo – for whatever reason – is subsequently removed from the internet website, I still have my own personal copy of it on my computer. Now, does the same hold true for videos? If I see a video that I like – and I want to have my own copy of it before it (potentially) gets removed from the internet – how can I download (save) that to my computer? Or is that not even possible? I tried a few steps, but I could not seem to make it work (or certainly not as easy as it is with photographs). Thanks. Joseph A. Spadaro (talk) 05:21, 9 July 2014 (UTC)

This is usually easy.
  • Try dragging the image to your desktop or into a folder.
  • Try right-clicking the photo, then "save as..."
  • The command can vary, depending on browser, but usually, there is an equivalent command in the r-click menu.
However, some sites protect their images, to reduce illegal re-use of their content. It doesn't work on the WP logo either, because the logo links to the main page.
Hope that helps. - ¡Ouch! (hurt me / more pain) 06:23, 9 July 2014 (UTC)
Actually, it works on the WP logo (which is not CC-BY-SA btw) if I use the left button (I'm using FF30); I tried right-button dragging. Fail. - ¡Ouch! (hurt me / more pain) 06:29, 9 July 2014 (UTC)
Thanks. But you misread my question. I said that I know how to do this for photos. I was asking about how to do it for videos. Thanks. Joseph A. Spadaro (talk) 07:04, 9 July 2014 (UTC)
It does depend a bit on the site your want to download the video from. For YouTube try doing a search for download youtube videos which will give you several different plugin and websites you can use. Probably safer to use a website as some of the plugins can be full of adds. This PC advisor article is relatively current. --Salix alba (talk): 07:22, 9 July 2014 (UTC)
Yes, it will depend on the site, Salix's links should be helpful. I'll add that some sites take extra steps to prevent you from easily downloading their videos. But, conceptually, anything that you can play on your screen (or speakers) can be captured and saved, see e.g. screencast. SemanticMantis (talk) 16:21, 9 July 2014 (UTC)
So, every individual site will require a different method? There is no "one size fits all"? Joseph A. Spadaro (talk) 17:25, 9 July 2014 (UTC)

The website has a fairly robust YouTube video downloader where (after installing the software) you can paste the URL of the YouTube video you want and hit download and it'll save it on your computer (you can also choose your output format and video resolution). For other websites, there are other methods (yes, I'm afraid there is no one single method that applies for all websites). However, the Internet Download Manager (another nifty software you can get by googling its name) adds a small plugin to your internet browser so that everytime you play a video on any site, it give your a small option button (which you get when you hover your mouse on the video) that lets you save it on your hard disk. As far as I remember, Real Player comes with a similar plugin too, which works only on videos, whereas Internet Download Manager can help you download images, videos, as well as music (even the background music playing on a site can be saved). Depending on your country, and how willing you are to bend the law, you can also obtain high resolution videos off Torrent websites (which are not, strictly speaking, legal. You've been warned.) Hope this helps. La Alquimista 18:52, 9 July 2014 (UTC)

Thanks. Is that Internet Download Manager free? Or requires payment? (And I am in the USA.) Thanks. Joseph A. Spadaro (talk) 22:38, 9 July 2014 (UTC)
Point of clarification: there is nothing illegal about using the Bit torrent protocol to "obtain high resolution videos." Some people do use torrents to obtain copyrighted material without paying for it, and that is illegal in many jurisdictions. But torrents can be used to share public domain video [9], open source software, and many other perfectly legal things. SemanticMantis (talk) 21:13, 9 July 2014 (UTC)
The critical thing here is how the video is presented on the web site. It can be just a ".avi" or ".mp4" file on the server that the browser downloads and displays - in which case, you can download it as a file. However, it's also possible for a server-side application to stream the video to you as your browser consumes only a small section of the video is available at any given instant. To "download" this, you'd probably have to capture it frame-by-frame using a program like fraps. The same problem *could* potentially occur with still images. I've seen a couple of sites that attempt to prevent people from downloading a large image by chopping it up into teeny-tiny bits. When you right-click on what you THINK is the entire image and select "Save Image" - it saves a tiny postage-stamp sized chunk - and while you THINK you grabbed the entire thing, you actually only got a tiny piece. However, you can still do a screen-capture to see the image.
In the end it's a matter of your determination and technical skill versus that of the person who is trying to prevent you from doing just that. However, in such circumstances, you're almost certainly violating their copyright you should probably "play nice" and not try too hard. SteveBaker (talk) 21:03, 10 July 2014 (UTC)

Lock files to prevent deletion by anything other than my program[edit]

I want to lock down some files in a folder to prevent other users from deleting/editing them. Then if my program wants to move or delete the file, it temporarily unlocks it, moves/deletes, then relocks it (if moved) to prevent deletion again. Essentially something/someone is deleting files on a drive and I need to do everything I can to stop it. It's an ancient IT system we are stuck with so it's likely the total lack of control or housekeeping over the years has casued something to go haywire.

I've read a bit about the filestream read-only property that would stop this by tricking the system into thinking the file is under use - Can I set this property without actually setting up a stream between the program and my file? Are there any other better ways in VB.NET? It needs to prevent file deletions/moves/edits by non administrators unless done so through the program.

Ultimate goal is to bit by bit lock a number of files and folders and only allow my program to move/delete files, this would ensure that only "approved" moves are allowed (I would use filesystemwatch to monitor "unapproved moves" by comparing a database of these with a database of "approved" moves). Thanks! (talk) 07:47, 9 July 2014 (UTC)

Something like that is possible, but is there a reason you can't use file system permissions? There are plenty of little gotchas that could make a program cause strange bugs by locking files like that. If only non-administrators only have read access to the files then you won't need a program to enforce it. Katie R (talk) 12:07, 9 July 2014 (UTC)
Agreeing with Katie. File system permissions is our article, if you are using an OS in the *nix family, you'd want to read up on chmod. No idea how it works in Windows, it didn't even have permissions until relatively recently. SemanticMantis (talk) 16:17, 9 July 2014 (UTC)
"Relatively recently" meaning 1993 with NT 3.1. :-) I vaguely remember using per-user file permissions in 98 SE but I don't think the file system supported it so I'm probably wrong... Katie R (talk) 16:46, 9 July 2014 (UTC)
Ah, well NT wasn't exactly for average home users, was it? My reading of the the article is that Win2000 was the first mass-market WinOS to have a real persmissions system. That was long after I stopped using Windows, and I daresay "recent" in terms of OS history :-P SemanticMantis (talk) 16:59, 9 July 2014 (UTC)
It wasn't a consumer OS, but it made the feature available to those who needed it. Windows 2000 was the first consumer version based on the NT kernel, although it was also mainly a corporate version. XP was the first widespread consumer version with support. I do agree that those operating systems can be described as "relatively" recent in OS terms, but your average reader may not realize just how far back it goes. 1993 is starting to get back there though - 21 years old on a list that goes back 63 years. Katie R (talk) 17:27, 9 July 2014 (UTC)
If this is a network with AD, you should be able to limit access to the directory to certain users. Alternatively, maybe you shouldn't be storing the files on a file system. Instead, create a database and store the files as BLOBs. A Quest For Knowledge (talk) 22:34, 9 July 2014 (UTC)

Keep in mind that if this were strictly possible, then malware could be written that could not ever be deleted through normal (i.e. not reformatting or anything) means. Instead I'd suggest file permissions as above.--Jasper Deng (talk) 04:08, 10 July 2014 (UTC)

Time Machine's schedule[edit]

How does Time Machine (OS X) decide when to do what? I'm guessing that it goes like this:

if the last complete backup was at least a week ago:
while the backup drive is too full for a complete backup:
delete the oldest backup;
do a complete backup.
else if the last daily backup was at least a day ago:
do an incremental backup relative to the last weekly backup;
delete any daily backups more than a week old.
else if the last hourly backup was at least an hour ago:
do an incremental backup relative to the last daily backup;
delete any hourly backups more than a day old.

Is this close? —Tamfang (talk) 08:24, 9 July 2014 (UTC)

This page has some nice technical descriptions of various aspects [10]. SemanticMantis (talk) 17:10, 9 July 2014 (UTC)
Very interesting, though it doesn't touch on my question. —Tamfang (talk) 03:51, 11 July 2014 (UTC)

Unicode fonts with specific ligatures[edit]

I'm taking notes on my computer and I want to use tone markup like ˧˩, which is composed of two unicode characters ˧ and ˩. Any fonts that work? unifont fails to join the characters, but whatever google chrome uses for its address bar (and this page although not the edit box) works. Chrome settings page claims it is using Arial/Times New Roman, but perhaps they are some special built-in versions, since they don't seem to work in xetex. How do I find fonts with support for specific ligatures or characters? -- (talk) 18:03, 9 July 2014 (UTC)

After much searching I found two fonts: Charis SIL and Andika. They are both too thick for my liking, but then I don't have to use them for text, only these symbols. Unless I'm missing something big "font preview" sites are pretty useless when looking for rarely supported characters. -- (talk) 23:44, 9 July 2014 (UTC)

Regarding gmail account security[edit]

Dear Wikipedians:

While consolidating my gmail account security the following question occurred to me:

After someone hijacks my gmail account, wouldn't that person be subsequently able to change all the security settings, including cell phone number, rescue email address, backup addresses, security question, etc., etc.?

Is there such a thing as an "immutable" security object that I can set with my gmail account that can be fell back on in case my account is really, really hijacked? I am thinking things like my driver's license or social security number which does not change for the rest of my life.

Thanks, (talk) 22:36, 9 July 2014 (UTC)

I believe they ask for another email address when you sign up. If somebody stole your account, and tried to change that, then they would send a notice to that alternate email address. If you then contacted Google, knew the answers to all the old security questions (which hopefully they keep), and they noticed that all your security info had just been changed, they might be inclined to agree that your account had been hijacked. StuRat (talk) 00:38, 10 July 2014 (UTC)
2-step authentication goes some way to mitigating your concern - now the evildoers would also have to steal (or hack) your phone as well as find out your password. -- Finlay McWalterTalk 00:40, 10 July 2014 (UTC)
Yes, I actually had just such an experience a couple of years ago. I had set up the email account some years earlier for someone else I regularly helped. Not sure how but someone else got into the email account. A day or so of correspondence with Google via the alternative address and all was fixed. HiLo48 (talk) 07:47, 10 July 2014 (UTC)
Note that most hackers won't want to permanently steal your email address. They are there to steal the information there, like your address book, or perhaps send out emails pretending to be you. Once they have the info and you've told everyone in your address book that the account was hacked, it's of no value to them. StuRat (talk) 15:30, 10 July 2014 (UTC)

July 10[edit]

print something that can't be scanned[edit]

I've seen a document that can't be successfully scanned or photocopied. Is there an easy way to print something (at home) that can't be scanned or photocopied? Bubba73 You talkin' to me? 05:44, 10 July 2014 (UTC)

The paper, here [11], won't copy correctly. This paper, here [12], erases itself after 16-24 hours (not sure exactly what you need this for, thought I'd mention it). This typeface, here [13], claims that it will mess up OCR (again, not knowing the need, this may be something to look at).Phoenixia1177 (talk) 07:34, 10 July 2014 (UTC)
Another way would be to use a very light color, like yellow on a white background. StuRat (talk) 15:26, 10 July 2014 (UTC)
Thanks to both of you. Bubba73 You talkin' to me? 17:02, 10 July 2014 (UTC)

With the first paper. with the "void"s going diagonally, does that cover up black text well enough that a person can't read it? Bubba73 You talkin' to me? 20:33, 10 July 2014 (UTC)

My understanding is that the 'void's will make it more difficult, but not impossible to read the text. Think of tamper resistance, compared to tamper-evident packaging. The former resists entry, while the latter just makes it apparent. In the case of paper documents, if someone can photocopy the original, they can presumably also read the original (or even re-type it, etc). The point is not so much to prevent copying, but to prevent a copy as being passed as the original, by making it evident that it is a copy (I also wonder if the 'void' markings would show up if someone took a photo of the page...) SemanticMantis (talk) 21:04, 10 July 2014 (UTC)
Thanks. Bubba73 You talkin' to me? 17:41, 11 July 2014 (UTC)

Some graphic designers and print editors use "non-repro blue" (aka 'non-photo blue') ink pens for making margin notes etc. but i'm not sure if it's a special ink, or just the certain color which photocopiers can't read well... nonetheless i think you might be able to achieve a similar effect with normal inkjet/laserjet, using certain shade(s) of light blue. And you may know this already: any capable photoshop pro can get around most deterrents like this or the others mentioned above. If you're talking about protecting images (e.g. minimizing potential of unwanted reporduction), I suggest reducing the image's resolution. i do this with some photos i post online. El duderino (abides) 21:05, 11 July 2014 (UTC)

Win 7 Windows Explorer wildcard search by file name[edit]

FWIW, I hate the Windows 7 file searching facility. Everything it does is awkward or not possible.

I have many folders full with mostly numeric filenames, eg 123-4567-8.pdf. I have discovered the name: tag and can search for "name: 123-45" or "name: 123-45??", both of which work. A few of the files also have a couple of extra characters, eg 123-4567AB-8.pdf, and both "name: 123-45??AB" and "name: 123-45??AB*.*" find no files.

If I shift-rightclick the folder and type into the command line "dir /s 123-45??AB*.*" it lists the files, so they are there.

How can I find such files?

BTW, in an idea world I'd just type "AB" and it would return all files whose names include the sub-string "AB", but that is an unachievable desire!

-- SGBailey (talk) 08:54, 10 July 2014 (UTC)

I hate the search too. I use an alternative search, Super Finder XT (if I want a gui) or more usually Cygwin find and/or grep --TrogWoolley (talk) 13:41, 10 July 2014 (UTC)

Creating images automatically with information from an Excell document[edit]

I need to create some graphics for display on monitors hanging in our factory. They need to be automatically generated from Excell files at regular intervals. What I need is some method of automatically putting Excell data into a graphic form. I've never seen anything that can do this, and I'm hoping one of you has a suggestion for me. Thanks in advance. Zzubnik (talk) 21:25, 10 July 2014 (UTC)

Can you specify what you mean by "graphic form" ? Pie charts, bar graphs, etc. ? Also, are you a computer programmer ? Here's an outline of the steps needed:
1) Keep a background job running running continuously (you might need to restart it, manually or automatically, if it crashes or the system is rebooted, but an automatic restart could potentially crash the system). At the specified interval, it will do the following:
2) Export data from Excel in a usable form, such a CSV file.
3) Kick off a program to read that data, convert it to whatever type of graphic form you want, then save it as a file.
4) Kick off a program to distribute that file to the computers hooked up to the displays, and display it on them, or, if they all have access to the same directory, store it there and have them all display from the same file (although this might cause a file contention issue, so you might want to stagger the intervals at which each monitor updates it's display).
Something else you might want to consider is screen screen burn-in. That is, with certain display technologies, displaying the same thing on a screen continuously will degrade the display. So, for example, if the X and Y axis on a graph are always the same, those may be burnt into the screen at some point. To reduce this, you might want to draw them at slightly different locations each time, by offsetting the entire image a bit in the X and Y direction with each run. StuRat (talk) 13:33, 11 July 2014 (UTC)
Hi StuRat, and thanks for the input. These are pretty much the steps I was envisioning. What I lack is the software that can take in data (excell, CVS, etc) and render it to a graphic. The software would be scheduled to re-create the graphic at specific intervals, and would be saved at a central location, which the various PC's driving the screens would be connected to.
I've got a half-way solution involving two spreadsheets and a macro in Powerpoint sucking in the data as an embedded object, but I can't format the text in the way I'd like to yet.
I used to be a programmer, so I am capable of light programming. If I had time, I'd knock something together in VB or similar. I'm going to have a re-think over the weekend. Thanks again for the help. Zzubnik (talk) 14:31, 11 July 2014 (UTC)
Can't this be done in Excel itself with VBA? -- SGBailey (talk) 14:58, 11 July 2014 (UTC)
Quite possibly, but I'm not so good with VBA in Excell. I will do some research over the weekend. Thanks for the suggestion. Zzubnik (talk) 15:09, 11 July 2014 (UTC)
I would do this with gnuplot or packages for the R_(programming language), or perhaps NumPy depending on what I needed to display. The type of images/charts/graphs etc that you want may dictate the most convenient tool, as will the other tools that you are already familiar with. E.g. if you are already familiar with R, that's the best bet. SemanticMantis (talk) 15:59, 11 July 2014 (UTC)
  • I'm not sure I understand the question. Excel itself has plotting functions that allow you to create graphs of a spreadsheet that update automatically when the data in the spreadsheet changes. If those aren't sufficient (they're kind of primitive), you can get add-ons such as SigmaPlot that give you greatly enhanced graphing capabilities. Looie496 (talk) 21:21, 11 July 2014 (UTC)

July 11[edit]

Need a clever solution[edit]

This is a Wikipedia question that may be best asked here:

Is there a clever solution that would get around the need to rename the archives? Anna Frodesiak (talk) 07:04, 11 July 2014 (UTC)

Well, if the search function doesn't include the archives, the search function could likely be changed to do so. However, note that most people doing a regular search probably don't want to find archived results, so a separate search of the archives, or perhaps a single search with check boxes for whether to search current articles, archives, or both, might be in order. StuRat (talk) 13:31, 11 July 2014 (UTC)


i need to view the predefined superclass of a class in java and for that i used javap <classname>.it works fine in jdk6 i mean, i defined a class and just need to show its inherited from works but when i tried same thing in jdk7 or jdk8 i dont get java.lang.object i.e the class profile doesnot show the predefined superclass in jdk7and jdk8.i dont understand why? (talk) 17:55, 11 July 2014 (UTC)

It is an intrinsic part of the language and the VM spec that all classes either directly extend java.lang.Object or extend a class that (recursively) does so. For a direct subclass of java.lang.Object, it's redundant for javap to explicitly say "extends java.lang.Object". There are various bugs in the Sun and OpenJDK trackers where they debate what the "right" thing is for it to do, including 6715757 and 7031005. They seem to have finally resolved, in the timeframe you note, that the appropriate thing to do is not to do so. -- Finlay McWalterTalk 18:30, 11 July 2014 (UTC)
I've looked a bit further at the source repository for JDK7. It's a bit of software patch hokey cokey. Prior to July 2008, the source for javap in JDK7 had code to suppress printing "extends java.lang.Object". Then they added printing it (back) in with this patch. But in March 2011 they took it out, with different code, in this patch. I've not looked in the patchsets for JDK6. -- Finlay McWalterTalk 21:48, 11 July 2014 (UTC)
Okay, here's the rest of the explanation:
  • Up to and including JDK6, there wasn't special code to handle this case, and it printed "extends java.lang.Object".
  • In 2007, for JDK7, they rewrote javap (details). I've checked the source for the two versions of javap, and the JDK7 version looks to be a clean rewrite with nothing much in common with the legacy version in JDK6 (which seems to date from the dark ages of Java1.x). Whoever did the new version decided not to print it - so they put in explicit code to suppress printing it.
  • That code was removed in 2008, as I noted above
  • New code to suppress it again was added in 2011, again as noted above
And that's where things are now. -- Finlay McWalterTalk 22:13, 11 July 2014 (UTC)