Wikipedia:Reference desk/Archives/Computing/2010 April 13

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April 13

Traveling salesman problem and taxicab geometry

How does the complexity of the traveling salesman problem change if the distances are determined by 2-dimensional taxicab geometry and constrained to have at least one integer coordinate (meaning they must be on "streets" but not necessarily at intersections? NeonMerlin 04:07, 13 April 2010 (UTC)

Travelling_salesman_problem#With_metric_distances says that the Manhattan metric case is still NP-complete. I don't see how the constraint to have one integer coordinate changes this - as far as I know, you can specify the TSP on integers to begin with. Going from any rational TSP to an integer variant is just scaling, and computers (even abstract ones) don't do really real numbers, anyways. --Stephan Schulz (talk) 07:40, 13 April 2010 (UTC)

Windows XP Pro doesn't boot

On boot, the computer would hang on the screen with the Windows logo and the running bar beneath. Boots fine if I press F8 and choose Last Known Good. How do I fix it so I don't have to press F8 each time? (Tried system restore, doesn't work. Can't reinstall because it is in French and I don't have the CD.)F (talk) 06:12, 13 April 2010 (UTC)

You need to reinstall. Contact your computer manufacturer and ask for a copy of the CD. Or try Microsoft. Ale_Jrb^talk 13:52, 13 April 2010 (UTC)

I used to have a similar problem. It was eventually cured by disabling a defective graphics driver. You can get XP to show you what is loading when it starts up. As far as I recall mine used to hang after it had loaded mump.sys (or some similar name). Mump.sys was working OK, it was what it did next that was the problem. Unfortunately XP does not tell you what is happening at that point. Try restarting it in Safe Mode. If it loads up in Safe Mode, then something it is loading in ordinary mode is the problem. 89.240.34.241 (talk) 22:55, 13 April 2010 (UTC)

information technology

Electronic Commerce enables an organization to operate in the areas much beyond their physical relation” Elaborate

WP:HOMEWORK. That said, you might appreciate the article on electronic commerce. Dismas|^(talk) 10:48, 13 April 2010 (UTC)

Question about editing PHP and javascript files

I'm a programming novice. I made some small fixes to the sidebar in my website, using the following method. I feel like there must be a more efficient method, and I am wondering if you can suggest one, for the next time I need to do so.

The main challenge was FINDING the file that contains the sidebar. To do so, I first went to one of the pages on which the sidebar appears, and used the "inspect element" tool in firebug to find some identifying feature of the sidebar. In this case, it contained an identifying number, #######. Then, I downloaded the page in Filezilla and searched for " #######" in the original PHP file. In one of the locations where ####### appears, I saw the name of a javascript file. I downloaded that file, and, hallejuah, it is the place where the sidebar is stored. (For confidentiality, I won't provide the file name, but I did a google search and can tell you that it bears a generic resemblance to this file). Is there a more efficient method to locate the file that contains the sidebar?

The next challenge was editing that file. Is there a more efficient method than downloading the file in Filezilla, editing the text in Mac OS "Text edit", and uploading it again? JD Caselaw (talk) 12:59, 13 April 2010 (UTC)

1. No, sorry, there isn't really a better way. Why not? Because there are about a million different places that could be stored, depending on how the website was set up. If one knew that the site was set up in a predictable way (e.g. it was a WordPress site and was set up like most generic WordPress sites are), then you could say, "Oh, this kind of site always keeps its data here." But if not, then you have to either go through the code (which won't be very helpful if you aren't experienced in reading code and know how Javascript/CSS/HTML/PHP files transclude content), or, as you did, find something that will search through all the files for the right text. So I would say you're doing it pretty efficiently for someone with your professed novice ability.

2. Basically all file editing is a version of what you are describing—get content, edit it, upload it again. There are programs that can automate some of that. I think TextWrangler can let you directly save to an FTP server, skipping some of the laborious bits. It's also a more full-featured text editor than Text edit (and is free). There are other methods that are similar that are available, but they're all of the same nature. --Mr.98 (talk) 13:50, 13 April 2010 (UTC)

(edit conflict)It depeneds entirely on who wrote the code for the site - quite frankly, they could have put anything, anywhere they wanted. If there isn't any documentation, and you can't ask the person that wrote it, then there isn't any magic way to find it.

With regards to editing a site, do you not have a local copy of the files? You should do. You can then perform any 'find/replace' etc. and editing on your local copy, then just upload any changed files to the server. This helps if you have to change server, or if your host goes down etc. Ale_Jrb^talk 13:51, 13 April 2010 (UTC)

(edit conflict)That is indeed how one would generally maintain one's PHP website. Strictly, if one wanted to be safe, one would have a locally-hosted copy (running off a local apache or whatever) that one would use for experimentation and development and would then push changes back to the live site only when confident that they're okay. There's no substitute for understanding one's codebase, and while PHP is perhaps more amenable to tinkering that other web development systems, it's still a complete programming language, with the capabilities, and risks, that brings. Navigating the sourcebase (of your local copy) will probably be a bit easier if you use an Integrated Development Environment which is PHP aware - this article compares the PHP features of several IDEs. Incidentally you're right to hate FTP, not just because it is clunky but because it is insecure; see if your web host supports SSH instead, and if it does use WinSCP edit: an SSH/SCP client to move your files to the site. If you end up doing a lot of development, you'll probably have a "publish" script that automatically pushes changes from your development copy to your live site (using something like rsync over ssh). -- Finlay McWalter • Talk 14:00, 13 April 2010 (UTC)

Although if you are just worried about security, you could use FTPS if it's supported (which may or may not be more likely then SSH) Nil Einne (talk) 16:54, 13 April 2010 (UTC)

Thanks everyone!!! 207.237.228.236 (talk) 20:30, 13 April 2010 (UTC)

If you have shell access to the server and it is a Linux or Unix server... Once you knew the number (lets say it was 12345), you could quickly find which file(s) contain that by typing at the command prompt grep 12345 and pressing enter. You'd see a list of which files match the string and what the line that matches looks like. -- kainaw™ 04:04, 14 April 2010 (UTC)

Opera Mini proxy for other browsers?

Opera Mini uses Opera servers as a proxy to render web pages into a faster format (see here). Would it be possible to make a plugin for another browser (say, Mozilla Firefox) that can utilize this same functionality too? The main benefits would be speed (if you are on a slow connection) and anonymity (because of the proxy). Now, I know that I can already run Opera Mini directly on my PC using a Java ME emulator, like MicroEmulator; but having to use the phone interface is awkward and inconvenient. I want to be able to use the typical Firefox buttons and keyboard shortcuts and bookmarks and stuff, but have the browsing done through the Opera Mini protocol. Has anyone done anything like this? It would be kind of analogous to when one uses a third-party instant messenger client instead of the official AIM, MSN, Yahoo, or whatever clients. Thanks, --169.232.246.47 (talk) 19:58, 13 April 2010 (UTC)

This would be difficult to accomplish because as far as I know, only Opera (the company) knows how their special markup language works. This could be reverse engineered, but it is also far more complicated than a simple IM protocol. Most third party IM clients only support text chat and a few basic "extra" functions for protocols that are not open source. These protocols can change at any time and if Opera Mini's rendering engine, markup language, or any component necessary to display a web page were to change, the plugin would no longer work. You see this with the multi-protocol IM clients from time to time, and I could only imagine that it would be worse with Opera Mini. It could be done, but I'm not surprised that no one has put the effort into doing it. Caltsar (talk) 20:24, 13 April 2010 (UTC)

Much of the speedup is to be had by downsizing images and removing content that's not appropriate for the small-footprint environment (like java applets or flash). Some of this can be achieved with a web accelerator, which has the advantage of retaining the normal web protocols and file formats while reducing bandwidth (and, depending on the context, maybe latency). -- Finlay McWalter • Talk 20:38, 13 April 2010 (UTC)

I know in the past (don't know if they still do, perhaps it's on by default but you can disable it) Vodafone NZ use to do the downsizing images and perhaps other things when browsing through a mobile Nil Einne (talk) 23:25, 13 April 2010 (UTC)

XP Pro SP2 Blue screen

Windows XP on start up blue screens with: "BAD_POOL_CALLER" Tech Info: " ***STOP: 0x000000c2 (0x00000040, 0x00000000, 0x80000000, 0x00000000". Safe modes OK. Restore point to: -30 days no help. Any pointers before a reload of the OS? 70.177.189.205 (talk) 23:32, 13 April 2010 (UTC)

Prior to it going sour, did you notice your PC behave in any unusual manner? 24.189.90.68 (talk) 04:22, 14 April 2010 (UTC)

Yes, At Windows logon, upon logging on, it would say "Loading" and then bounce back to Windows logon.70.177.189.205 (talk) 10:23, 14 April 2010 (UTC)

Did this start to happen after you installed a particular program/hardware/update? It could be a driver problem. 24.189.90.68 (talk) 00:25, 15 April 2010 (UTC)

If you are being logged out instantly it is usually due to a bad profile. Try logging in under a different user, or go into safe mode and try to log into the Administrator account.