Wikipedia:Reference desk/Archives/Computing/2011 September 20

= September 20 =

Python matrix module
Does anyone know of a matrix module for python that can:
 * Create a matrix out of vectors
 * Replace rows and columns in matrices
 * Add and multiply to every element of a vector except the last (which will be kept as a 1 so I can use matrices for translation)
 * Multiply a matrix by a vector (M*v) instead of just the other way around (v*M)
 * Provide enough documentation that I can actually find out how to do these things

I've tried to find one on my own, but I failed.

Thanks. — DanielLC 03:53, 20 September 2011 (UTC)


 * I'm pretty sure NumPy can do all this. 130.88.99.231 (talk) 10:00, 20 September 2011 (UTC)


 * It doesn't have vectors. Also, I can't replace columns, and I can't find good documentation. — DanielLC 03:01, 21 September 2011 (UTC)
 * It does have vectors, although "vectors" in this case are simply matrices with a single dimension, rather than two (or three or more). (There isn't a specific vector type, but there still is all the *functionality* of vectors.) For replacing a column, use the array assignment and slice notation ( m[:,2] = (4,3,2,1) # Replace the second column with the vector (4,3,2,1) ). As to documentation, there's a tutorial, as well as a User Guide and a Reference Guide. There is also a Guide to NumPy book which at one point cost money, but now is available for free (ignore the PayPal buttons and click the "Guide to NumPy" link). There's also Sage, which is not quite a module, but is based on NumPy (along with some other things) and has additional documentation, some of which may be applicable to NumPy proper. As a last resort for documentation, there's always Google/Bing/etc. Unless you're doing esoteric things, searching for things like "numpy create a matrix out of vectors" is likely to get you a webpage or a mailing list post that discusses the issue. - Frankly speaking, NumPy is the "standard" matrix package for Python, and you're unlikely to find anything for Python that's more comprehensive in features or as well documented. -- 174.24.217.108 (talk) 05:13, 21 September 2011 (UTC)

Net access for Ubuntu in a virtual box
I have Virtual Box running Ubuntu on a laptop, which I'm on now, that has WinXP installed. I can't get Ubuntu to connect to the net though. I thought maybe I could use a work around and have one of the Windows folders show up in the virtual box but haven't succeeded there either. Can anyone help? Dismas |(talk) 07:54, 20 September 2011 (UTC)
 * Try setting the Network to "Bridged Adapter". --Phil Holmes (talk) 08:24, 20 September 2011 (UTC)
 * On which OS? I'm no expert at WinXP and I'm new to Ubuntu.  So please give me more details.  Thanks, Dismas |(talk) 08:30, 20 September 2011 (UTC)
 * On your Virtual Box settings.--Phil Holmes (talk) 10:01, 20 September 2011 (UTC)
 * That still doesn't work. Dismas |(talk) 10:05, 20 September 2011 (UTC)
 * Can you connect to the outside world at all? What IP addresses do your PC (cmd window and ipconfig) and Ubuntu VM (terminal, ifconfig) have?--Phil Holmes (talk) 10:58, 20 September 2011 (UTC)
 * This is now in the archives but I'm going to reply here anyway. It's now working.  I have no idea why though.  I asked for help from my school's IT help desk and they couldn't make any progress either.  Then tonight while working on an assignment, the VM started up with a functioning network connection.  Dismas |(talk) 08:58, 27 September 2011 (UTC)

foreign characters when I want English
I'm in Britain on a 'British' computer using a standard British keyboard. I use up-to-date Firefox. I'm trying to type in English into a form on a "foreign" website, but my letters come out as the script of that language. I've googled for a solution and thoroughly checked out Firefox options and can't seem to turn off this 'feature'. Help please! — Preceding unsigned comment added by 195.27.52.146 (talk) 12:00, 20 September 2011 (UTC)


 * I've never seen this myself. Could you provide the link to the website? It'll let us figure out if its FF that's doing this, or the website. --Mr.98 (talk) 12:02, 20 September 2011 (UTC)


 * It's a Wikipedia page, . I tried it on Chrome and IE7 too and they also 'forced' me to write in that script.  195.27.52.146 (talk) 12:32, 20 September 2011 (UTC)


 * There seems to be some clever JavaScript to intercept key strokes and insert the georgian characters. I would love an explanation of how it works! Edit - I just confirmed this by disabling JavaScript, then I can type English characters. Really they should not be doing this, it will make setting up interwiki language headers very hard. -- Q Chris (talk) 12:43, 20 September 2011 (UTC)


 * Clever - look for the checkbox above teh search bar with "ქართულად წერა" next to it. (I have no idea what that means). Clear this check and you will be able to type using your native keyboard language. -- Q Chris (talk) 12:50, 20 September 2011 (UTC)


 * Ah! Thank you.  You think they could have at least put an English remark next to the tick box.  It is clever but it is also annoying because I spent a fair amount of time wondering what was wrong with my browser.  195.27.52.146 (talk) 12:55, 20 September 2011 (UTC)


 * We really want someone to come up with a glyph/symbol meaning "no keyboard mapping". This seems to be used on a lot on non-English wikis, and an English remark wouldn't necessarily help someone entering a Hindi interlink on the Georgian page or vice versa. Maybe somenthing like "a➔ა" in a No symbol would do as a symbol. -- Q Chris (talk) 13:18, 20 September 2011 (UTC)

Tax Calculation For An Employee(male/female) in c programming.
How can a C program be created for an employee(Male/Female) using swith, if else, functions and array? Please help me. I can't get it.Its confusing.Kamal.sharma535 (talk) 16:42, 20 September 2011 (UTC)


 * What tax calculations are you trying to do ? In other words, please list the full specifications for the program. StuRat (talk) 17:07, 20 September 2011 (UTC)


 * (ec) This depends entirely on how the data is represented. For example, if the variable is "gender" and the values are 'm' or 'f', you can use:
 * As for doing it with an array or switch or ternary operator... it all depends on the formula and data structures. -- k a i n a w &trade; 17:09, 20 September 2011 (UTC)
 * As for doing it with an array or switch or ternary operator... it all depends on the formula and data structures. -- k a i n a w &trade; 17:09, 20 September 2011 (UTC)
 * As for doing it with an array or switch or ternary operator... it all depends on the formula and data structures. -- k a i n a w &trade; 17:09, 20 September 2011 (UTC)


 * You're really going to have to describe what the program is meant to do before we can give you much help. Show us some of your current thinking and/or work. We won't do your homework for you, but we're happy to give suggestions. --Mr.98 (talk) 19:01, 20 September 2011 (UTC)

Computer Age
Which computer age are we living in presently ?? — Preceding unsigned comment added by 41.66.234.139 (talk) 21:01, 20 September 2011 (UTC)


 * Your question is kind of unclear. What possible computer ages do you think exist? There are lots of different ways you could define a "computer age" — in terms of social aspects, processing capacity, artificial intelligence, etc. --Mr.98 (talk) 22:07, 20 September 2011 (UTC)

The cheap computer age. ¦ Reisio (talk) 00:54, 21 September 2011 (UTC)

Some people use the phrase Information Age, by analogy with the three-age system (but see the "Criticism" section in that article, as "Information Age" suffers from some of the same problems) to reflect the fact that humans now widely use tools that are made of (and manipulate) information. I've never heard of people use "age" with any greater granularity than that. Paul (Stansifer) 00:58, 21 September 2011 (UTC)


 * I've heard "Networked Age" (which is more specific than Information Age, which we've technically been in since at least the 1960s, probably earlier), and I've heard "Petabyte Era" (less commonly, "Petabyte Age"), which are quite different in what they are talking about (one is about the exponential boom of computer connectivity since the 1990s; the other is about the sheer gobs of data being routinely processed in the last decade or so). This is why I asked for clarification. --Mr.98 (talk) 02:12, 21 September 2011 (UTC)


 * The Internet Age ? StuRat (talk) 04:44, 21 September 2011 (UTC)


 * I noticed we have some "generation" articles - in terms of computer languages we have reached the fifth generation, see Programming language generations
 * More generally useful might be Category:Computing timelines
 * A few sources distinguish between hardware generations eg http://knol.google.com/k/brief-history-of-computers# I'm not sure how widespread this definition is Imgaril (talk) 12:25, 21 September 2011 (UTC)