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December 14

Conflict with YouTube?

I have noticed a problem lately. When I play a video on YouTube, and -- at the same time -- try to scroll a Wikipedia page (using my mouse wheel), it makes the video skip until I stop scrolling. I haven't tried any other site. How can I get this to stop. Allen (Morriswa) (talk) 01:00, 14 December 2012 (UTC)

Can you try scrolling in another way, perhaps with the scrollbar ? StuRat (talk) 05:24, 14 December 2012 (UTC)

Also, which OS and which browser do you use? --Stephan Schulz (talk) 08:04, 14 December 2012 (UTC)

I haven't tried the scroll bar. I use Windows XP, Service Pack 3 & Mozilla Firefox 17.0.1. I hope that helps. Also, I'm now noticing the issue with other websites, like Google, for example. Allen (Morriswa) (talk) 02:45, 15 December 2012 (UTC)

Well, some OSes, especually older ones without compositing window managers (which Windows only got with WIndows 7) will stop screen updates during some operation like e.g. scrolling. If that is the reason, the sound would normally continue. And the same thing should happen with other Web browsers, at least if all use the Flash plugin to play YouTube. --Stephan Schulz (talk) 09:14, 16 December 2012 (UTC)

I have this problem with my parents laptop, its so incredibly slow and full of horribel software (Norton etc) that even youtube slows it to a crawl. I've found that it is so slow it can't process the video and scrolling a densely populated webpage at the same time, sometimes even crashing IE/Firefox. If yours is similarly slow, you might want to think about reinstalling the OS. 80.254.147.164 (talk) 12:06, 17 December 2012 (UTC)

Both Vista and Windows 7 (and now Windows 8) have the Desktop Window Manager. Nil Einne (talk) 07:03, 18 December 2012 (UTC)

Make sure your video drivers are the latest available from the manufacturer's website. Windows will work with built-in drivers, but often won't take advantadge of the card's capabilities to accelerate things like scrolling. 209.131.76.183 (talk) 15:19, 17 December 2012 (UTC)

Firewire 400 power clash?

I want to connect an old iMac to a DVR using a Firewire 400 cable with 6-conductor alpha connectors on both ends. I believe that both devices are prepared to provide power to the other via the Firewire cable. Does the IEEE 1394 standard protect against this, perhaps with blocking diodes to prevent the device with lower supply voltage from suffering a reverse current driven through the cable by the other device having a higher supply voltage?50.4.23.161 (talk) 05:11, 14 December 2012 (UTC)

Firewire can be used to directly connect two computers, which strongly implies that this shouldn't be an issue. However, I haven't found a reference specifically addressing your concern. Generally (but not always), user-accessible ports on a computer are pretty well protected against excessive current drain, short circuits, improperly applied power and other common problems, simply to avoid accidental damage to internal components due to a failure in a peripheral. (I know this from working with this sort of protection circuitry.) 209.131.76.183 (talk) 16:41, 14 December 2012 (UTC)

Citroen website and javascript causing reboots

Hi, last week i could go to Citroen.co.uk or any other international Citroen site to look around or waste some time. This week i've noticed that my computer reboots when these pages are loading, yet doesn't do it on other sites. Google sources suggest this may be a javascript issue, but i am unsure how to fix it without disabling javascript in Firefox 17.0.1 on Windows XP, or why the issue has appeared since last week. Any recommendations? Thanks ツ Jenova20 ^(email) 10:41, 14 December 2012 (UTC)

Changing Directory by command line

On a Unix system, I can type

cd <pathname>

and my current directory is immediately set to that path, even if I was previously in a different file system.
However on Windows, to change to a different drive, I have to set the drive letter explicitly as well, and (as far as I can tell) the cd command has no effect until I have done so. Has Microsoft ever commented on why they did it this way, and does a two-stage process present any advantages over doing it in one? Rojomoke (talk) 11:15, 14 December 2012 (UTC)

You're mistaken on cd having no effect if you're in a different drive. In fact for most/all? Microsoft non POSIX NT command shells it will change directory for that drive. If you later change drive, it will be in the directory you changed to. And if you do something to a relative path of the drive, it will be to the directory you changed to. (E.g. if you are initially in D:\Temp2, you change to drive C: and then cd D:\Temp and then copy something to the directory D:Files, it will be copied to D:\Temp\Files\ not D:\Temp2\Files\ or D:\Files\.) I believe this was the same for MS DOS command shells (including Windows ones), but I can't recall off hand. Nil Einne (talk) 11:23, 14 December 2012 (UTC)

BTW, this behaviour is discussed at cd (command) which confirms it originated in DOS and is preserved for backwards compatibility in NT command shells like cmd.exe, although it doesn't give a reason for the origin of this behaviour. (I suspect it at least partially has to do with the fact Drive letter assignment exists in DOS as well as the fact independent working directories can be useful when your storage and file systems are organised in such a manner and so changing working directory without changing drive can also be useful.) Nil Einne (talk) 11:32, 14 December 2012 (UTC)

This in fact a very useful feature now. It was quite frowned upon when RAM was scarce (640k) because it used one directory string per drive letter. Thus you needed to limit the number of drive letters via LASTDRIVE=F - saved space which would have gone to twenty unused drive letters otherwise.

Now it is useful. Say you have utilities on floppy (A:), you can type c: then cd \MyDocuments\images\holiday\2012\summer and still call an exe which is on A:\. What if it is in A:\UTIL? No prob. cd A:\UTIL Now say pkzip is what you want and make an archive on your external HDD which happens to be E:, and you want it in the folder E:\backups\other. cd E:\backups\other Now you can pkzip the images:

a:pkzip e:h2012s.zip *.*

If you had no working directories on a per-drive basis, you would have needed

A:\UTIL\pkzip E:\backups\other\h2012s.zip *.* instead.

Oh no! There's no more free space on E: Let's say it happens during photo 60 of 60, so a tighter compression method is what you want. What would you prefer,

a:pkzip -ex e:h2012s.zip *.* or

A:\UTIL\pkzip -ex E:\backups\other\h2012s.zip *.*  ?

In a nutshell, it is as Nil said. You can specify directories via drive letters only. x:file.ext will be the file in the working directory, while x:\file.ext will be in root. - ¡Ouch! (^{hurt me} / _{more pain}) 13:08, 14 December 2012 (UTC)

Thanks to you both. I see that for my purposes (only ever referring to one drive at a time), I need to use "cd \d". Rojomoke (talk) 16:08, 14 December 2012 (UTC)

Who really made Instagram unusable (directly) over Twitter?

I've read on news sites that Twitter made the change to their systems so that Instagram photos cannot be seen directly in Tweets, but only links to the pictures. But when updating the iPhone Twitter app, the "what's new" section included "Instagram has decided to disable its integration with Twitter and as a result, photos are no longer appearing in Tweets or user photo galleries." 67.163.109.173 (talk) 11:57, 14 December 2012 (UTC)

I don't know what "news" sites you're reading, but most sites seem to confirm Instagram is the one which disabled the integration [1] [2] [3] [4]. Since even the Instagram CEO agrees, [5], [6], [7] (well I didn't check what he said myself), I guess those news sites didn't know what they were talking about. As the earlier links mentioned, Twitter have responded in various ways (as have other companies). Nil Einne (talk) 17:47, 14 December 2012 (UTC)

Variable substitution not working with delayed expansion variable (Windows XP)

Hi,

I'm under Windows XP and I'm encountering the problem described here: in a .bat file, I don't manage to extract a substring from a delayed expansion variable: in the .bat file, I wrote:

setlocal enabledelayedexpansion
FOR /F "delims=" %%n IN (%1) DO (
md "z:\blah\%%n"
set y=%%n
set a=!y:~0,2!
[...]
)
endlocal

and on my screen (with ECHO ON), I get:

C:\temp>FOR /F "delims=" %n IN (toto.txt) DO (
md "z:\blah\%%n"
set y=jzocbz
set a=!y:~0,2!


(whereas "a" should be set to a substring of "jzocbz").

Any ideas?

Thanks. Apokrif (talk) 17:30, 14 December 2012 (UTC)

-> bottom of [8]. Apokrif (talk) 10:20, 8 January 2020 (UTC)

mobile internet abroad

I live in Britain and have a smartphone on contract with 3. I'm travelling to Germany (and briefly to Luxembourg) very soon and would really like to still be able to use the internet on my phone - emails, maps, travel information, etc. I've noticed that the prices I'll be charged by 3 for doing this abroad are horrendously expensive. What are my other options? Would it be simple to get a German card and put it on my phone, pay as you go? (My phone is unlocked.) I think I've seen some kind of International card in airport shops before. How do they work? Are they expensive? 92.13.65.59 (talk) 18:22, 14 December 2012 (UTC)

It would be helpful if provided information about the mobile operator that you user and what is your current tariff plan. Ruslik_Zero 19:33, 14 December 2012 (UTC)

Well, as I said, I'm with 3. On the contract I get a number of free minutes, texts, and GB of data per month for a fixed price. I'm not sure why it's necessary to know that though - I want to know what I can get in Germany or at the airport which will allow me to operate more like someone who lives there - paying a resident's prices (instead of being fleeced by my network for travelling). 92.13.65.59 (talk) 19:43, 14 December 2012 (UTC)

Generally speaking in most countries there's no such thing as a 'resident's prices'. If you mobile phone is with a foreign provider and you roaming in that country, you will pay for the service (although my impression is the rates aren't quite that bad in the EU but I think internet is still an area the regulatory agencies are working on). The alternative is to buy a local SIM and pay whatever domestic rates associated with the account you are on rather then roaming although remember if you charging SIM you are charging your account, you will have a new phone number and everything. In most countries this will have to be a prepaid SIM, since it will be difficult or impossible for a non resident to start a contract in a foreign country (but these still aren't resident prices, they are simply on account or post paid prices). I would avoid buying a SIM card at an airport particularly a foreign one, you will likely pay for the service. It will almost definitely be far better to buy a SIM card from within more normal shops in Germany. Even if you don't speak German it shouldn't be that hard to find a shop where someone has a sufficient command of English to help. Since you're primarily interested in mobile internet, bear in mind prepaid mobile internet prices can sometimes be a fair amount dearer then on account/postpaid ones. You may want to look out for bundles and do a fair amount of investigation beforehand to find the best deals. Nil Einne (talk) 07:51, 15 December 2012 (UTC)

(OP) Thank you very much for all of this information. It's very helpful! 62.159.40.248 (talk) 15:41, 15 December 2012 (UTC)

this site has a list of different prepaid carriers in Germany and instructions for how to activate data packages. As Nil Einne said, prepaid SIM cards are available in many different retail stores; they all seem to have a pretty high basic cost per MB but also offer daily/monthly data packages that are much better value. 59.108.42.46 (talk) 09:57, 17 December 2012 (UTC)

Official North Korean Instagram?

A former coworker's photo on Instagram was liked by North Korea... @northkorea_dprk_officialsite (http://web.stagram.com/n/northkorea_dprk_officialsite/) which calls themselves "Official Site of the DPRK (North Korea)". Is this true? They liked her image of a gingerbread cookie. -- Zanimum (talk) 18:46, 14 December 2012 (UTC)

I doubt if that site is run by the North Korean government. They seem to be as incompetent at web technology as they are in feeding their own people. A decade ago, I viewed their English web site, which was translated into English far worse than a machine translation, including listing the name of their nation as "Koran". :-) StuRat (talk) 19:09, 14 December 2012 (UTC)

Thanks! I presume everyone else agrees with this assessment? -- Zanimum (talk) 16:07, 15 December 2012 (UTC)

Installing Firefox 17 without administrator rights

I'm trying to install Firefox 17 on my Windows 7 system. When I run the setup .exe file, it says I have to log on as an administrator. I'm the only person who uses this PC and have never set up an administrator account for it and there is no password. If I click the radio button to install it as a regular user, it stops installing. If I click the radio button to install it as an admin but leave the password blank it says I can't leave the password blank. If I click the radio button to install it as an admin and type some madeup password as the password it says the password is wrong. Is there anything I can do short of continuing to use Firefox 16? This never happened when I upgraded Firefox in the past. Angr (talk) 19:33, 14 December 2012 (UTC)

That's weird, but why are you running an installer instead of just letting Firefox update itself? ¦ Reisio (talk) 20:55, 14 December 2012 (UTC)

It tried and said that didn't work. Didn't say why not, though. Angr (talk) 23:15, 14 December 2012 (UTC)

Well now this time it did work. So it's updated now. Thanks for your help! But it still sucks that it wouldn't work with the installer. What will I do next time I buy a new computer and want to install Firefox for the first time? Angr (talk) 23:22, 14 December 2012 (UTC)

I doubt you'd run into this bug on an entirely new OS install, but if that does happen, come on back we aren't going anywhere. (Or even try http://webchat.freenode.net/?nick=Angr&channels=##windows) ¦ Reisio (talk) 00:41, 15 December 2012 (UTC)

Your account normally is the administrator account, so it should work if you enter your account's password. If that doesn't work, try going into the Control Panel and changing your account type to Administrator (if it isn't set to that already). Or, as a last resort, you could try right-clicking on the setup file and choosing "run as administrator". I hope this helps. WikiPuppies _bark ^dig 03:15, 15 December 2012 (UTC)

To clarify WikiPuppies point somewhat, starting from Windows Vista, User Account Control means programs will generally not have full administrative access even if you are running from an administrator account, which in most installations will be the default account. You need to specifically grant permission when the UAC panel comes up. However the panel will only come up if the program either says it needs administrative permission or Windows decides it does (which it does for all things with install or setup in the name IIRC). Since UAC has been out for a while, most programs which need it should ask but in the event you are having problems, it's always helpful to choose 'run as administrator' to see if that's the problem. While you can turn of UAC, I strongly discourage it if you are going to be running as an administrator by default, particularly if your knowledge of using computers and Windows is not very high which from this discussion it probably isn't. If you want to check what your account type is and see what accounts are present, one of the simplest ways is to open the Control Panel, click on 'Add or remove user accounts', grant permission if asked and see what it says. Nil Einne (talk) 08:08, 15 December 2012 (UTC)

Whooops um it just occurred to me the final recommendation probably won't work if you aren't actual an administrator. Nil Einne (talk) 09:17, 15 December 2012 (UTC)

As the only user of this computer, I ought to be an administrator, since no one else is. And when I open User accounts on my control panel, it even says my account is named "Administrator". I don't have a password for my account, because as the only user of this computer I never saw the point of having one. I could create one, but it would be just one more damn thing for me to have to remember, and I worry that then I would have to sign in every time I start up my computer, which is a pain in the ass on a computer in my own apartment that no one has access to but me. Angr (talk) 17:14, 15 December 2012 (UTC)

I've also seen this behavior, where a Windows computer that formerly logged directly in, without asking for any password, suddenly starts asking for one. It's not the result of an update or user change. It's a bit of a mystery how or why this happens, but I've seen it occur. StuRat (talk) 17:30, 15 December 2012 (UTC)

Well it's probably best to just make the computer auto-login again rather then worrying too much about why or how it happened. Anyway there's probably no need to create a password for your account in the setup described by Angr however you will still have as I mentioned UAC does mean you will still have to run programs as administrator if they don't request elevation but need it. I'm a bit surprised Angr's account is named Administrator, that isn't recommended by Microsoft any more and in most normal set-ups the account named Administrator is hidden and disabled but perhaps OEMs ignore Microsoft's recommendations. Nil Einne (talk) 08:42, 16 December 2012 (UTC)

Loading values of a Java HashMap as needed from file

Hello! In Java, I need to create a dictionary of String-List<MyObject> pairs, write it to a VM-independent file, and then load that dictionary in an Android application. The Android application just needs to read from the dictionary, never add values to it. For the moment, I'm only concerned about the Java (Oracle JVM) side. To attempt this, I've tried using HashMap<String, List<MyObject>> and serializing it to JSON with Google's GSON. I've run into the following problems:

1. I have several String keys that map to the same List<MyObject> value, but GSON insists on re-writing the List<MyObject> for every key. This isn't a problem with respect to filesize, since the file will be compressed, but it will probably cause the same object to be redundantly loaded into memory for each key, since it doesn't seem GSON knows they're equal.
2. The Lists contain instances of MyObject as well as instances of MyObjectSubclassA, MyObjectSubclassB..., but while GSON supports serializing generics, it deserializes them all as the superclass MyObject, discarding any functionality (e.g. method overrides) provided by the subclasses (even though examination of .json file shows the additional fields of the subclass are being written, there is no CLASSTYPE marker in the .json file that tells GSON what subclass to instatiate. This possibly can be corrected with some setting in GSON...).
3. With this implementation, the whole HashMap has to be loaded into memory from the file. It would be nice if there was some Java implementation of a dictionary that loads all the keys and then loads the values from the file as needed.
4. I guess the serialization problem isn't a problem if I just run the dictionary-creating code with the Dalvik-VM default serialization and extract the created file from Android device image. However, the Android API gives very little guarantee that serialized objects will be future compatible, so it would be best if the dictionary is serialized to a standardized format like Json, or have the dictionary explicitly handle its own serialization.

I appreciate your advice on how to handle any of these points. I'd also greatly appreciate any advice on an alternative implementation to solve the original problem I laid out. Thank you!--el Aprel (^facta-_facienda) 22:06, 14 December 2012 (UTC)

It would help us understand if you can give us examples. If the data is proprietary, please make up some data to show us what you mean. StuRat (talk) 22:47, 14 December 2012 (UTC)

(e/c with Finlay, about to read what he wrote...)Here's an example: Say I want a dictionary of Employees by department, listed by seniority. So I use a HashMap<String, List<Employee>> dict. I initialize it and add all the keys and values, so if I call dict.get("IT"), I get a List of all Employees in the IT department. I also put that same list under the keys "technical" and "computer people", so dict.get("technical") returns the same exact List as dict.get("IT"). (Problem #1: If I write this HashMap using Google's open-source json-file writer, GSON, the same List of Employees gets rewritten under "technical", "computer people" and "IT".)

Subclasses of Employee have additional contact information that needs to be displayed, like LegalEmployee and HumanResourcesEmployee. (Problem #2: GSON doesn't know List<Employee> contains subclasses of Employee, such that, after deserializing from the Json file, employee.displayContactInformation() always calls Employee.displayContactInformation(), never LegalEmployee.displayContactInformation().)

Rather than include the code that initializes that HashMap from scratch in my application, I want to include the HashMap in a file in an Android application, so that people can type in a department as see who works there. If someone just wants to look up who works in IT, the application shouldn't have to load all the Employee objects in the HashMap, just the List of those returned by dict.get("IT"). (Problem #3)

Hope this helps illustrate what I need to do and the problems I'm having. Thanks!--el Aprel (^facta-_facienda) 23:16, 14 December 2012 (UTC)

Thanks. It really sounds you need a relational database to do what you want properly. You may be able to get by with a non-DB approach, with a small enough amount of data, but it won't scale up well. StuRat (talk) 23:34, 14 December 2012 (UTC)

Thank you, StuRat. Yes, this problem is probably suited for a database, but it's actually overkill for what I'm working on, which, in terms of this example, has a fixed number of employee that, once created, never needs to be altered or updated, so scalability isn't a problem.--el Aprel (^facta-_facienda) 23:52, 14 December 2012 (UTC)

I don't know much about GSON specifically (and you're sure to get better answers than mine on the GSON google group), but in general:

1. It seems you're trying to render a cyclic object graph into the acyclic JSONformat: specifically it sounds like GSON is just doing a basic iteration over the map, and (because JSON doesn't have a concept of a "reference") it just generates a new entry for each entry it finds. You could take control yourself, and instead emit a JSON array for the keys, another for the values, and a third for the mapping between the two (where the mapping is an array of integer pairs, [k,v], where these are indices into their respective tables. Then you have to manually build the structure back yourself on deserialisation.
2. dunno
3. In the worst case, you can write a little class (that implements java.util.Map) that keeps the string data in a java.io.RandomAccessFile and that only loads into memory a HashMap that associates the key to a (int position, int length) tuple. When someone does a get(), it effectively fseeks(position) and read(length) to generate a new object on the heap. That's a horrid thing to do on a spinning media file, but perhaps not on the flash devices you'll see on Android. Or you could do something similar with java.nio.MappedByteBuffer; whether its RAM usage strategy works better for your application, I don't know.
4. My concerns regarding the fragility and non-interoperability of using the language's serialize functionality, which I added earlier today to your previous question, apply here just as much. If you do decide to use this approach, I'd recommend you read all of the serialization chapter of Josh Bloch's Effective Java (it's chapter 10 of the first ed.); Bloch's rather stentorian warning at the start of that chapter would still the ardour of many the serialize fan.

-- Finlay McWalterჷTalk 22:54, 14 December 2012 (UTC)

Very helpful, Finlay, thank you. Your advice in #1 for making the HashMap Json-friendly is a stellar idea. I'm going to start implementing that and check back here for anything else you or others might want to add.--el Aprel (^facta-_facienda) 23:52, 14 December 2012 (UTC)

Lithium-ion cell phone battery

I have an old cell phone that works just fine, except that the 6 year old battery doesn't hold much of a charge (I have to recharge it every night). I ordered a "new" cell phone battery, and they sent me one which is 7 years old. I am displeased. However, is it possible, that if this battery has been on a shelf all this time, it will hold a charge better than the newer battery I'm using now, which has been in continuous service for 6 years ? I'm wondering if I should test it out first, or send it back right away. StuRat (talk) 22:28, 14 December 2012 (UTC)

We don't seem to have any experts on Li-on here (you might try the Science Desk). My understanding, which is probably no better than yours, is that it depends a lot on how the 7-year-old battery has been maintained and stored. Some batteries being manufactured now could well be in good condition if treated carefully for the next seven years, but this is less likely to be true of one manufactured seven years ago. I'd be inclined to contact the seller and ask what percentage of original specification capacity they guarantee. Dbfirs 23:27, 16 December 2012 (UTC)

OK, I will repost there. StuRat (talk) 00:09, 18 December 2012 (UTC)

December 15

disc full - can't delete

On my Windows 8 system, one of my external hard drives got 100% full. Now I can't delete anything - it says that the destination does not exist. Perhaps it is talking about the recycle bin. I've tried moving some files to another disc, but it says the same thing. I went to the command line prompt and tried to delete there, but it didn't actually delete. Is there a way to delete some files in a situation like this? Bubba73 ^{You talkin' to me?} 03:24, 15 December 2012 (UTC)

Try a defrag to combine some unused space into usable amounts ? Another option might be to delete something huge, which always tells me "That's too large for the recycle bin, do you want to delete it instead ?" (this was under Windows XP, though). StuRat (talk) 03:36, 15 December 2012 (UTC)

There is only one file huge enough to get the "too big for recycle bin" message, and I don't have enough room to copy it to another drive. Bubba73 ^{You talkin' to me?} 03:45, 15 December 2012 (UTC)

Try ⇧ Shift+Delete on a file to delete it without moving to the recycle bin. PrimeHunter (talk) 03:50, 15 December 2012 (UTC)

Thanks, Shift-delete worked. Now I can clean off some files and get enough elbow room. Incidentally, defrag would not start. I told it to empty the recycle bin, but it was empty. I did have 1.91GB free on the 3TB drive, but that wasn't enough. Bubba73 ^{You talkin' to me?} 03:53, 15 December 2012 (UTC)

Resolved

Wikisource content is being indexed as Wikipedia content (in Google)

For some reason, Google is indexing some content of Wikisource as Wikipedia content, see this. I have faced it before too. Any idea? --Tito Dutta (talk) 20:56, 15 December 2012 (UTC)

Googlebot must have come by a page with the link http://en.wikipedia.org/wiki/S:The_Complete_Works_of_Swami_Vivekananda/Volume_3/Lectures_from_Colombo_to_Almora. S: is a interwiki prefix for Wikisource so the link redirects there. PrimeHunter (talk) 21:23, 15 December 2012 (UTC)

Swami Vivekananda, specifically. Note that, given Google's often very fast handling of changes and new pages, there are strong indications that Google has special handling for Wikipedia articles - that they're not indexed in the same way regular web pages are. I suspect it's following the recent changes feed and is pulling articles (or diffs) using the MediaWiki API. If it gets the wikitext for that article, it will get the S prefix. I think the effect we're seeing here is an artefact of this - Google's magic-wiki-spider handles this subtly differently to how the MediaWiki wikitext renderer does - the latter generates a normal wikisource.org url, the former presents it as a wikipedia.org url even though it isn't one. -- Finlay McWalterჷTalk 21:50, 15 December 2012 (UTC)

What makes algorithms non-deterministic?

Hi! In the article deterministic algorithm we say, that threads can cause race conditions, which is a non-deterministic behavior. Or is it a misunderstanding? I'm no native speaker... :-) I have a liltle problem with that claim and in de:WP they couldnt solve my problem: I cannot believe, that a bunch of concurrent, deterministic algorithms transform into a non-deterministic algorithm (in the sense of the formal definition given in the article). E. g.: In a deterministic computing machine M the concurrent algorithms A1 and A2 each load data object O to register X, increment X, write X to O and halt; in my understanding this cannot ever produce more than one sequence of states (e. g. M starts up with 2 identical cores, which each use the same clock and memory without any caching or locking, so that they will behave as if there was only one core, if there wasnt the extra boredom+heat - esp. after the halt instruction). But nobody wants to believe me... *sob* :-) Could somebody explain me, where my example becomes non-deterministic? Is it possibly a homonym thing? Thx. Bye. --Homer Landskirty (talk) 21:00, 15 December 2012 (UTC)

The "What makes algorithms non-deterministic?" section of that article is specifically talking about real computers, stuck here in the muddy real world with us. They don't behave like your mathematically perfect deterministic computing machine. If you were to simulate a cycle-perfect machine, with everything (including interrupts and so forth) simulated deterministically, then algorithms within it would behave deterministically. But real computers, where timing is determined by analog events like the rotation of disks, the magnetic fields and air cushions beneath flying drive heads, the action of interference on bus lines, and a thousand other things, means interrupts which drive the OS don't behave perfectly deterministically, so threats aren't scheduled deterministically, and so a multithreaded algorithm will be affected. -- Finlay McWalterჷTalk 21:11, 15 December 2012 (UTC)

oh - ok - so there is a deterministic algorithm in the sense of theoretical informatics (e. g. with that funny turing machine, which has infinite memory... *lol*) and a real world deterministic algorithm concept (where random events r somehow compensated as good as possible... e. g. timing seems to b always indeterministic here, because there is no way to tell the exact time in real world... this allows race conditions to show up...)... --Homer Landskirty (talk) 22:11, 15 December 2012 (UTC)

In a theoretical context a nondeterministic algorithm is one where you assume a probabilistic distribution on its source of random bits and prove rigorously that the algorithm succeeds with some probability very close to 100%. In the real world the distinction is somewhat arbitrary—it comes down to whether you consider the source of (alleged) randomness to be part of the input or not. -- BenRG (talk) 22:23, 16 December 2012 (UTC)

oh - i thought about that today... without satisfying results: e. g. the program ssh-keygen asks for user input in the beginning and now i wonder if the algorithm is non-deterministic or not... the article says, that Fermat primality test is an example for a non-deterministic algorithm, although it just checks if an equation holds with different values for a... i think i will not try anymore to understand what they mean... :-) "functional programming" looks like a C program to me, too... sometimes... :-) it's a little bit like in that cartoon Calvin and Hobbes, when the father tells Calvin, that an outer point on a LP disc moves faster than an inner point, although they both do the same rounds per minute... *giggle* but it feels good, that i m not the only one who has problems with it... :-) --Homer Landskirty (talk) 23:01, 16 December 2012 (UTC)

The Linux ssh-keygen opens /dev/urandom and reads 32 bytes from it. That's randomness collected from real world sources like network and disk delays (hmm, I'd have thought it would use /dev/random, which is a better source still). -- Finlay McWalterჷTalk 23:20, 16 December 2012 (UTC)

the data from /dev/*random could still b seen as input to an deterministic algorithm... --Homer Landskirty (talk) 06:57, 17 December 2012 (UTC)

Actually, when I think about it, theoretical nondeterminism often means angelic nondeterminism, where one magically chooses the path that causes the algorithm to terminate as quickly as possible (for example, a nondeterministic factoring algorithm starts by correctly guessing a factor). That sort of nondeterminism is the N in NP. It's not directly related to randomness, since there may be only one best choice. What I described above would be called a probabilistic algorithm. I never thought about it, but this doesn't match the real-world use of "nondeterministic" very well at all... -- BenRG (talk) 00:35, 17 December 2012 (UTC)

maybe that's where my disturbance come from... we heard something about "demonic non-determinism", too... *giggle* it guesses wrong until it would have to do the same error twice... --Homer Landskirty (talk) 06:57, 17 December 2012 (UTC)

December 16

Google Instant

On my Google Toolbar in IE9, Google Instant search results do not appear. Instead, a more traditional list of results comes up, but just in a pop-up window below the bar. Altering search settings does nothing to fix the problem. Does anyone have any idea what might be occurring? It's not much of a problem, but I've found it a bit unusual. dci | TALK 01:56, 16 December 2012 (UTC)

Testing wifi link

I have a remote computer (linux) behind a router (the two connected via wifi on wlan0) to which I set up port forwarding for ssh (local ip 192.168.1.3) I don't have physical access to the computer. At some point I could not access the computer anymore, so I asked somebody with physical access to connect router and computer with a cable and to set up port forwarding for this connection (local ip 192.168.1.3; device eth0). Now I can connect to the computer again, however I need to set up the wlan only connection again, without cutting myself off. Is there a way to check whether wlan0 is working while eth0 is present as well? Or is there a way to disconnect eth0 (in software) for a while and have it automatically reconnect after some time? bamse (talk) 07:56, 16 December 2012 (UTC)

ping takes a -I option to allow you to specify which interface (eth0, eth1, wlan0, etc.) to use

to turn an interface off and then on: ifdown eth0 ; sleep 30 ; ifup eth0

-- Finlay McWalterჷTalk 12:24, 16 December 2012 (UTC)

Thank you. As for the ping, that would be issued from the remote computer, no? If so, it would only confirm whether the wifi link to the router is working and not whether port forwarding works, correct? bamse (talk) 18:16, 16 December 2012 (UTC)

Yes, it only validates that traffic is going out that way, not that an external device will preferentially send data in that way. All I can think of for the latter is to run tcpdump -i wlan0 and then send a bunch of traffic from some remote machine that should be relayed to the subject machine (by its local router) over wlan; you should see tcpdump report a bunch of packets (more than the usual network background chatter that it'll probably see). -- Finlay McWalterჷTalk 18:32, 16 December 2012 (UTC)

Or, rather simpler, netstat -i wlan0 will show you the number of packets received on that interface since it was brought up. As above, if you send the machine a bunch of packets you think should be delivered on that interface, if that's the case then that statistic should increase quickly. -- Finlay McWalterჷTalk 20:11, 16 December 2012 (UTC)

Thanks a lot. Thanks to your help I managed to fix it. bamse (talk) 23:34, 17 December 2012 (UTC)

Skyrim help

I don't know if this belongs here or on the Entertainment desk, but bear with me. I just purchased Skyrim for the PC, and when trying to attack, I'm told to press M1 or M2. But I'm on a PC with a keyboard. What are M1 and M2 on a keyboard? 216.93.234.239 (talk) 23:16, 16 December 2012 (UTC)

Mouse button 1 and Mouse button 2 (generally left and right mouse buttons). Incidentally you might find the default set has your left mouse button control your right hand, and vice versa - if so, you can (and really should, it drove me mad until I did) change it in the control settings. -- Finlay McWalterჷTalk 23:28, 16 December 2012 (UTC)

Thanks, just trying to figure out what they were talking about was driving me crazy.  :) 216.93.234.239 (talk) 23:31, 16 December 2012 (UTC)

December 17

PC Memory stick as Random-Access Memory

What is an efficient way to use a 32Gb USB memory stick as RAM? The stick behaves like a hard disk but I don't want directories and files, I just want random access to bytes as fast as possible. My application is solving large sets of simultaneous equations held as matrices in RAM. Assume small programming knowledge. I might manage disk read/write at DOS interrupt level but have no idea how to address a USB interface. DreadRed (talk) 10:21, 17 December 2012 (UTC)

With a memory-mapped file. But the USB bus is orders of magnitude slower than RAM, so it will work that much slower than RAM, regardless of how you address it. -- Finlay McWalterჷTalk 10:39, 17 December 2012 (UTC)

You'd be better off buying lots of ram. Memory is cheap, how much is your time worth? But either way matrices can be worse than you think because of the way they access memory. There's all sorts of programming tricks people do to even get better memory access with proper ram so the cache is used better, it isn't easy as obvious tricks like aligning on page boundaries and chunking in small squares can lead to less obvious problems like cache thrashing where a cache line is overused. Dmcq (talk) 12:46, 17 December 2012 (UTC)

Although this is only related to your question indirectly: What do your matrices look like? Are they sparse? In that case your memory requirement goes down significantly. Also using an iterative solver rather than a direct elimination method will reduce memory requirements significantly.31.54.249.205 (talk) 00:01, 19 December 2012 (UTC)

Word frequency tables

Can anyone help me find these in the format I want ? Here's what Wiktionary has: [9]. Here's what I would like different:

1) No numbers or formatting text, just the words, in order from most common to least (one word per line in the file). This part is critical.

2) All the words in a single file, as opposed to files for the first 10000 words, next ten thousand, etc. This part is optional.

3) All non-alphabetic characters, like apostrophes, stripped off. This will make duplicates out of words like "cant" and "can't", so those should be combined into one, at the proper location in the file (the total of both frequencies). This part is optional.

4) Common proper nouns should be included, too. This part is optional.

I prefer US English, or both US English and British English, but not British English alone. So, do we have anything like that out there ? StuRat (talk) 16:45, 17 December 2012 (UTC)

Given a source list of frequency tables (can you specify), as long as they are in some regular format it should be trivial to merge in your desired form with a bit of custom software (I'd do it in QBasic!) . -- SGBailey (talk) 17:04, 17 December 2012 (UTC)

Possible, but not exactly trivial. It would take me several hours, and I'm already planning on rearranging the files to suit my needs, so I'd prefer if they are at the proper starting point already. StuRat (talk) 17:08, 17 December 2012 (UTC)

Given that you already play with Python, this is not really hard. Do you want to work with the Wiktionary tables, or do you want to create your own from a text corpus? In either case, as long as your result tables fit main memory (and that should be true even for very large word lists today), it's a simple application of some string operators, sort, and print. --Stephan Schulz (talk) 23:45, 17 December 2012 (UTC)

You may have better luck searching for concordances. I hopped over there, then to the Corpus_of_Contemporary_American_English, which led me to their concordance product here: [10], which is viewable as an html table. If you sign up, they will send you an .xls file, from which you can easily port to a single-word-per-line raw text file. Only catch is, only the first 5k words are free. Because it is a professional grade research tool, they charge for the full 100k database. SemanticMantis (talk) 20:16, 17 December 2012 (UTC)

Depending on your application, you may or may not be worried about the methodological details that make the COCA list rather different than the wiktionary list. COCA gives you full details of why their product is better, here [11]. SemanticMantis (talk) 20:19, 17 December 2012 (UTC)

I'm amazed this isn't available for free, like lists of prime numbers are. StuRat (talk) 00:07, 18 December 2012 (UTC)

That frequency list is from TV shows... so I guess you're looking for speech. Wikipedia would produce a different set of course. If you have a few sources with a lot of words (maybe a million?) you could run through and generate your own.

Here's what I ran from the command line to get most of what you want (assuming you have a mac or linux, or can otherwise run perl). Copy paste the list into a text file, or all in order if you want to do more than one at a time, then run this (you can break it up of course too):

cat wordlist.txt|perl -pe 's#^\d+\s*(.+?)\s+.*#$1#;s#[^\w\n]##g'

That won't combine duplicates (there are 4 duplicates in the first 1000), for that here's a dirty way to do it (you probably should have enough ram for this, but depending on your list size, beware): cat wordlist.txt|perl -pe 's#^\d+\s*(.+?)\s+.*#$1#;s#[^\w\n]##g'|perl -e 'while(<>){$word{$_}=$x;$x++};foreach(sort {$word{$a} <=> $word{$b}} keys %word) {print}' Shadowjams (talk) 03:07, 18 December 2012 (UTC)

The apostrophe in "can't" is not essentially a non-alphabetic character because it represents the character "o" that is hidden in the standard contraction of the two words "can not". English contains many such examples such as "it's" which means "it is" (or "it has" but nothing else, occasional abuses notwithstanding). DreadRed (talk) 08:37, 18 December 2012 (UTC)

My code handled it fine. Shadowjams (talk) 14:07, 18 December 2012 (UTC)

How to disable "Accessibility features" in Windows 7 ?

I apparently held the shift button down too long, and it tried to "help" me by beeping at me and locking up the keyboard. A reboot solved it for now, but how do I prevent Windows 7 from ever doing this again ? StuRat (talk) 17:45, 17 December 2012 (UTC)

This has been in there since at least Windows 98. To disable it in 7, open the Ease of Access Center (in the Control Panel, just use the Start Menu search). Under "Make the keyboard easier to use", you'll find the settings to disable the various keyboard accessibility features. The one you're looking for is under "Set up Filter Keys", but you'll probably want to disable the other ones as well. 209.131.76.183 (talk) 18:19, 17 December 2012 (UTC)

Thanks. I had "Turn on filter keys" unchecked, and assumed that was sufficient. But apparently you have to pick "Set up filter keys" to disable the "feature" of it turning back on when you hold down the shift key. StuRat (talk) 18:34, 17 December 2012 (UTC)

Those options drive me crazy when they are accidentally triggered, but I suppose that it makes a world of difference for people who don't have good enough control of their hands to use the modifier keys as designed - they can sit down at any computer and be able to turn on the feature without fighting through menus that are hard for them to use. For my personal computers I always turn it off, but I can see why it is on by default. 209.131.76.183 (talk) 19:03, 17 December 2012 (UTC)

lol,this can be helpful for me to,Thank you.74.178.177.48 (talk) 21:01, 17 December 2012 (UTC)

Resolved

Oldest Computer stuff

Hello fellow users, I'm Tailsman67,I'm a freelancer hacker and programer and I'm here to ask,"What is the oldest Computer?" and "IS the first Computer really the first?" and "What is the first program?",thank you? — Preceding unsigned comment added by 74.178.177.48 (talk) 21:06, 17 December 2012 (UTC)

See History of computing hardware - as with a lot of inventions, which the first X is often depends on how you define exactly what X is. -- Finlay McWalterჷTalk 21:12, 17 December 2012 (UTC)

Ada Lovelace's algorithm for calculating Bernoulli numbers on the Analytical Engine is often described as the first computer program - see Ada lovelace#First computer program. If my memory serves, I think it has a bug. -- Finlay McWalterჷTalk 21:15, 17 December 2012 (UTC)

Weren't the first programs the punch cards you switched to make your water- or steam-powered loom weave a different pattern? I'm not sure that counts as a Turing machine-like thing, though. Sagittarian Milky Way (talk) 23:08, 17 December 2012 (UTC)

A Sundial is the oldest analog computer. This one is from Marcianopolis. DreadRed (talk) 08:55, 18 December 2012 (UTC)

A similar example I heard of were hand-cranked organs, like this one: [12]. You could load a new program by replacing the cylinder, or edit the program by changing the pegs. StuRat (talk) 01:17, 18 December 2012 (UTC)

I seem to remember reading that Leonardo da Vinci had made a programmable toy out of wood and springs, basically a robot. ¦ Reisio (talk) 02:55, 18 December 2012 (UTC)

Yes, and the ancient Greeks did similar things. StuRat (talk) 21:02, 18 December 2012 (UTC)

This image shows one early use of computers. HiLo48 (talk) 09:50, 18 December 2012 (UTC)

Returning to the OP's question seriously, several of the first serious "electronic" computers were developed during World War II, and details of them were naturally hidden behind massive security at the time. Several countries have competing claims. While we now know a lot more, we cannot be certain that all details have been released. In fact, it's almost certain that some information has been destroyed forever. HiLo48 (talk) 16:52, 18 December 2012 (UTC)

Before the electronic ones the first mechanical one that was built that looked like a modern design was by Konrad Zuse and the first design like a modern one was Babbages. However one should really consider Zuse's initial machines as more like a modern scientific programmable calculator than a general purpose computer. Plus there were other systems in between like the Scheutzian calculation engine, based on Babbage's difference engine, Hollerith's tabulating and calculating machines which could be rigged together to do some quite complex work, and a complex number calculator which could be accessed at a distance via a teletype but however wasn't programmable. Plus all these were digital in operation, there were many analogue computers as well. Dmcq (talk)

If you'd like to see a reproduction of a programmable cart like Hero of Alexandria built there's one here [13]. He made some much more complex things too. Dmcq (talk) 19:27, 19 December 2012 (UTC)

What's the cheapest that 2GB DDR2 667 SODIMMs have been?

And when was that? Sagittarian Milky Way (talk) 22:50, 17 December 2012 (UTC)

Real cheap. Recently and now. ¦ Reisio (talk) 02:56, 18 December 2012 (UTC)

CamelCamelCamel is a great resource for this sort of question. Here's the price history on Amazon for a particular model of 2GB DDR2 667 SODIMM: [14]. You can use the search to find charts for others. 209.131.76.183 (talk) 12:45, 18 December 2012 (UTC)

December 18

DOS find command in Windows 7

I issue the following two commands in an empty directory, so neither should find any files to search:

find "call"  *

find "call"  *\*

The first command correctly says "File not found - *". The 2nd command hangs forever (but doesn't seem to use any CPU time). What's it doing, and how do I prevent it ? Also, is there a better way to repeat a search recursively in all sub-directories (all the way down) ? StuRat (talk) 01:09, 18 December 2012 (UTC)

You should be able to use PowerShell for a decent "native" grep alternative. You could also just grab a win32 build of grep from http://gnuwin32.sf.net/. ¦ Reisio (talk) 03:03, 18 December 2012 (UTC)

Grep won't work in Windows in this case because Windows doesn't see *\* as a valid path. Here's how I would search recursively for a string:

for /r . %i IN (*) DO find "call" %i

Other commands simply display an error that the path cannot be found or that is incorrectly spelled. But even if *\* was accepted by Windows, it would only search one level deep.—Best Dog Ever (talk) 03:08, 18 December 2012 (UTC)

grep works fine (and recursively) in Windows… if you have it. ¦ Reisio (talk) 03:24, 18 December 2012 (UTC)

What I was saying is that you can't search for a string in the Windows command prompt using the *\* wildcard no matter what command you use.—Best Dog Ever (talk) 03:30, 18 December 2012 (UTC)

Luckily you don’t have to, you can use . or the name of the top-level directory instead (and in fact wouldn’t want to use */* to "search recursively in all sub-directories (all the way down)", even if you could. ¦ Reisio (talk) 03:36, 18 December 2012 (UTC)

Thanks so far. So what exactly does my 2nd command attempt to do ? It behaves as if it's waiting for more input. StuRat (talk) 19:35, 18 December 2012 (UTC)

The help for Find (find /?) says: 'If a path is not specified, FIND searches the text typed at the prompt or piped from another command', and you're getting the first of those - try typing lines that do and don't contain "call". It seems to be a bit of a bug that it ignores the invalid filespec. AndrewWTaylor (talk) 13:17, 19 December 2012 (UTC)

SHA1 and MD5 collision attacks

I'm aware that both SHA-1 and MD5 have been broken with collision attacks. Some of which I guess can be run very quickly. But have there been any published attacks that can break both at the same time? In other words, find an arbitrary input that can collide with a predetermined sha1 and md5 checksum? Shadowjams (talk) 02:48, 18 December 2012 (UTC)

• The article Preimage attack covers what you are talking about. IETF RFC 4270: Attacks on Cryptographic Hashes in Internet Protocols contains references to published attacks. DreadRed (talk) 09:03, 18 December 2012 (UTC)

I know both discrete attacks exist, but does that attack apply to both on the same input block? The article doesn't seem to say as much. Shadowjams (talk) 10:05, 18 December 2012 (UTC)

Hashes are calculated independently for each 512-bit block so that is where collisions are sought. DreadRed (talk) 12:21, 18 December 2012 (UTC)

Alright, that's not an answer to my question. Shadowjams (talk) 13:26, 18 December 2012 (UTC)

You can't seriously hope to find a simultaneous attack on both SHA-1 and MD5, can you? DreadRed (talk) 07:49, 19 December 2012 (UTC)

Well that's the question. Never say never when it comes to cryptography. How long was it predicted MD5 would last in 1992? Shadowjams (talk) 20:20, 19 December 2012 (UTC)

FileMaker

Anyone use FileMaker?

I was asked if I could set up a members database and have it searchable, etc etc. The users are all around the world, so having it on a web site is best. In fact, optimally, they'd like the web site to pull data from the database for use on the site (showing lists of members, locations, how many members do we have that answered XX to YY question, etc). I've never had to set up a database myself, though I've installed and run a couple forums that relied on them. Shortly after being asked about this, the person who asked found FileMaker for another project that they're working on. They found it easy to use and now think that they might not need me to do anything. I took a look at the FileMaker web site and I don't see right off where it'll do what they want. Am I misreading things? Would they be better served by having an SQL database? Or is there some third solution that I remain unaware of? Thanks, Dismas|^(talk) 06:09, 18 December 2012 (UTC)

FileMaker is, as of version 12, a SQL database in its own right (from version 9 it could interact with other databases via their SQL interfaces). It does sound like, to make it accessible from around the world, you need a web app. FileMaker PRO does support this ([15]). To do that someone would have to code a webapp (in say PHP) which interacted with FileMaker (using their own API). Then you'd need to make that accessible on the web - it's likely that you'd get a FileMaker hosting solution (one that supports their Instant Web App capability - a web search finds lots of filemaker hosting companies) and host it there. They could certainly change to a different database, and / or write the webapp in another language (allowing different hosting); they could abandon their local database altogether and store the data in the cloud, and have everyone (including their own admin staff) access it by a webapp. But I think all of this requires engineering to write that webapp. -- Finlay McWalterჷTalk 15:25, 18 December 2012 (UTC)

Note (so you understand what you're looking at when you read some of the "FileMaker hosting" pages) - some organisations use FileMaker PRO as a kind of distributed groupware thing. Their employees around the world have their own copies of FileMaker PRO and they connect those up to a shared server to make changes (just as if they were back at HQ). It sounds like your members are just regular people who don't all own a copy of FileMaker, and so who can't avail themselves of this. That's why you need a webapp. -- Finlay McWalterჷTalk 15:30, 18 December 2012 (UTC)

Update: it looks like Instant Web Publishing means you don't need to write a webapp - they essentially have the FileMaker interface presented via HTML, which is done automatically. Writing a webapp is needed only if you want to have more control over how it appears and what people can do. Like other databases, FileMaker has security segregation between users - but if I were exposing a real database over the internet (particularly when you have to comply with various countries' data protection laws, which may be the case if you're storing details about people) then I'd want that set up by someone with lots of experience with FileMaker, so the security doesn't get cocked up. -- Finlay McWalterჷTalk 16:21, 18 December 2012 (UTC)

Thanks for the breakdown. It's a non-profit organization and they already have a web site. I don't know who they host it with. And you're correct in that not everyone would own a copy of FileMaker. After reading the link that you provided and reading over your explanation, it does seem like they might be able to do what they want with FM. Thanks again, Dismas|^(talk) 09:08, 19 December 2012 (UTC)

Playing Blu-ray discs on my computer

Is it just a matter of 'get Blu-ray drive, install drive, insert disc'? Or does my system need to be of a certain spec in order to play Blu-rays correctly? Don't really know much about them at all, TBH - just been musing over getting a BR drive for my computer now that my DVD burner is playing up on me... --Kurt Shaped Box (talk) 19:35, 18 December 2012 (UTC)

It should play immediately, once the drive and driver are installed. However, since Blu-Ray is capable of displaying a higher resolution image, the question comes up as to whether your PC can display it at full resolution, color depth, and frame rate without lagging. This involves the monitor, graphics card, GHz, etc. StuRat (talk) 19:38, 18 December 2012 (UTC)

That's a thought. My machine does lag sometimes when playing downloaded 720p/1080p HD videos (the latter moreso)... --Kurt Shaped Box (talk) 19:51, 18 December 2012 (UTC)

And the Blu-Ray player should have a minimum requirements list for your PC. That really is a minimum, though, meaning if you have anything else running while watching a Blu-Ray movie, you will need more oomph (technical term) to avoid lag. StuRat (talk) 20:20, 18 December 2012 (UTC)

No, you can't just rock up with a BluRay disc and get it to play. You need the right software to decode it. Often this will come bundled with the drive, unless it's an OEM device. See here and here for more. - Cucumber Mike (talk) 21:56, 18 December 2012 (UTC)

That's what I'm calling the driver, codecs included. StuRat (talk) 22:06, 18 December 2012 (UTC)

I'm pretty sure that I already have the required software installed anyway, but that's no biggie if not. I was more concerned about hardware requirements. Perhaps I should spend some of my probable Xmas gift money on a dedicated graphics card - what's considered good these days anyhow? It's literally been a decade since I paid attention to developments in computer hardware. My current machine has some on-motherboard graphic chipset thing that so far (mostly) works well enough for what I use it for... --Kurt Shaped Box (talk) 22:20, 18 December 2012 (UTC)

Is this a virus?

I had a program blocked today by my firewall, i think it was trying to send info to the internet. From the information it gives, it looks like a virus that is trying to pass as some legitimate windows program. Look at its location on the hard drive too! The folder name is so arbitrary.

http://i45.tinypic.com/1fd3yc.jpg

Is this a virus? Please share thoughts! :)

PS: I can't think for the life of me why i would have some crap from microsoft, with the publisher being russian...

137.81.118.126 (talk) 19:56, 18 December 2012 (UTC)

Looks iffy to me. I'd get rid of it. StuRat (talk) 20:16, 18 December 2012 (UTC)

I'd compress it with heavy algorithm, not into the file type .ZIP (since Windows natively supports it) and leave the compressed file there. You never know if it's actually legit; you may need it again. -- 143.85.199.242 (talk) 23:04, 18 December 2012 (UTC)

Appears to be a trojan common in Russian-speaking countries. If you don't already have it then please download MalwareBytes Anti Malware and scan the file as that is the recommended fix. MalwareBytes is pretty good at this thing anyway if you've never used it. Good luck! ツ Jenova20 ^(email) 23:42, 18 December 2012 (UTC)

Solve chess

How long would it that the Titan supercomputer to solve chess? — Preceding unsigned comment added by 67.60.98.242 (talk) 20:01, 18 December 2012 (UTC)

Depends on what you mean by "solve". If you mean to use a brute force approach to look ahead from the start of the game to all possible games, and use that to decide each move, that's not possible (would take longer than computer would last). StuRat (talk) 20:15, 18 December 2012 (UTC)

I am not interested in a practical application, an academic result will be sufficient. Are we talking decades, centuries, millenia or the age of the earth here? — Preceding unsigned comment added by 67.60.98.242 (talk) 20:21, 18 December 2012 (UTC)

Let's see. If you brute force it, this site says there are some 10¹²⁰ possible moves: [16]. That would take longer than the universe will last to solve. However, if you just look at board configurations, the number is far lower. This is because you can arrive at the same board position by many different sequences of moves. This site lists only some 140 million board positions: [17]. So, if you had each of those in the database, and the appropriate move for each, then looking them up should still allow for a perfect game, in a small amount of time. StuRat (talk) 20:35, 18 December 2012 (UTC)

Good idea. Is the reason that it has not been solved then because of the time to create 140M databases? — Preceding unsigned comment added by 67.60.98.242 (talk) 20:50, 18 December 2012 (UTC)

Yes. StuRat (talk) 20:55, 18 December 2012 (UTC)

Well, depending on what 67 means. If a (fast) oracle would hand you the correct move from any position, and if that's really all there are (I haven't checked that), then such a database would be perfectly feasible. The problem is computing the correct move. (What's a correct first move for White, for example?) --Trovatore (talk) 21:38, 18 December 2012 (UTC)

Oh, I guess you already went into that. Never mind. --Trovatore (talk) 21:39, 18 December 2012 (UTC)

To go a bit further, each pawn or piece can have it's board position modeled by 6 bits (3 bits gives us one of 8 horizontal positions, since 2³ = 8, and 3 more give us the vertical). Some pieces would need an additional bit, so a king stores whether it has yet castled, and a pawn whether it has been promoted to a queen. So, let's just round this 6 or 7 bits up to 8 bits, or 1 byte per piece or pawn. That's a complete board position modeled by 32 pieces × 1 byte, or 32 bytes (less as pieces are taken). Along with those, you'd want to store the next move, so maybe 4 more bytes for that (2 for white's move if it's white's turn, and 2 for black's). So, a total of at most, 36 bytes. Multiply that by 140 million possible board positions, and we get 5GB. That should fit easily on a hard drive, but for maximum speed, we'd want it in memory. A high-end PC could handle that. Add a proper index/hash to search through the board positions, and it could move basically instantaneously, from a human POV. However, actually generating all this data in the first place would take vastly more computation time. StuRat (talk) 20:55, 18 December 2012 (UTC)

Endgame tablebase could be relevant here. bamse (talk) 21:32, 18 December 2012 (UTC)

The source used above [18] gives no real argument for the alleged 140 million positions. It's a gross underestimate. Chess#Mathematics and computers says: "The number of legal positions in chess is estimated to be between 10⁴³ and 10⁴⁷". See also Shannon number and Solving chess. PrimeHunter (talk) 22:50, 18 December 2012 (UTC)

Expanding on the above, lets assume we can now build a computer storage array that contains the equivalent of one million 1 TB drives. That's 10¹⁸ bytes. Assuming that each position could be mapped to a unique address and we use roughly a byte of storage to store some piece of information (such as moves to win, loose or draw), we can represent roughly 10¹⁸ positions. Well short of our goal for now. Populating data for a game of that magnitude would not be a huge problem. Assuming 1 million processors calculating 1 million positions per second, they could process a universe or 10¹⁸ positions in as little as a few weeks. Note that all of these assumptions could be off by many orders of magnitude, but these are minor going into the next step of the estimation.

If we pick the middle ground for the total number of legal positions, say 10⁴⁵, we will find that our current technology falls short by a factor of 10²⁷ or 2⁹⁰. A liberal application of Moore's law, where both storage capacity and processing power double every two years, would place the expectation for a final solution 180 years in the future (give or take a couple of hundred years). Of course Moore's law is not guaranteed. A molecular crystalline storage device capable of storing 10⁴⁵ bytes might be the size and mass of a small moon.

Perhaps sometime in the year 2200, there will be a chess showdown between Ganymede and Titan, which uninterestingly always ends in an agreed draw before the first move. -- Tom N (tcncv) talk/contrib 04:17, 19 December 2012 (UTC)

python

how do you find the index of the largest int in a list? and how do i find what item occurs most often in a list? thanks, 70.117.119.138 (talk) 23:55, 18 December 2012 (UTC)

Both of these involve a simple iteration through the list, keeping tabs as you go. Have you tried to get this working youself - if so, please show us where you failed. For tasks that look like homework, you'll find Wikipedia editors will help you but they won't (for your benefit) do the work for you. 87.114.106.165 (talk) 01:48, 19 December 2012 (UTC)

For the first one, try "print myList.index(max(myList))". However, this will only return the first index with the max value. If there are more than 1, you might not want this behavior. "myList.count(max(myList))" will tell you if there are more than 1.

For the second, I think iteration is needed. Again, you need to think about what to do if you get a tie (2-way, 3-way or more). StuRat (talk) 19:39, 19 December 2012 (UTC)

December 19

List of non-x86 computers geared for home users?

Can you give me a list of non-x86 computers available to home users (routers excluded)? --83.84.137.22 (talk) 11:43, 19 December 2012 (UTC)

Raspberry Pi springs to mind - mostly since mine is right in front of me - but strongly suspect there is other cheap(ish) single board computers available. WegianWarrior (talk) 12:03, 19 December 2012 (UTC)

If you aren't looking for something new, then any PowerPC-era Mac will work. Devices that run Windows CE/Embedded Compact are often ARM-based. Many tablets and some low-end netbooks are ARM-based. Otherwise, you're looking into the single board computer world mentioned above. They are usually targeted for small kiosks, industrial control and digital signage, but there is no reason you couldn't use one as a home user. 209.131.76.183 (talk) 13:09, 19 December 2012 (UTC)

Updating XP in one session.

I've got an old Compaq Presario SR1520 NX running XP (don't laugh, it's fast enough for me).

However, it's time to replace the 320GB drive with a larger one, and re-install XP, which I've done several times in the past. I use the restore DVD's that came with the computer (service pack 2).

Each time I have re-installed XP, it seemed that, for a few weeks, there would be several updates each week. My guess is that the powers-that-be thought that one giant update would take too long for most consumers, so they limited each update so as not to take too much time (This is just a wild guess on my part).

I would like to update to the latest XP, no matter how long it takes, with one update session. How do I do that? And apologies if this is so basic that I should have known. Bunthorne (talk) 16:52, 19 December 2012 (UTC)

You should download and install XP Service Pack 3, instead: [19]. That should eliminate all those updates that were basically taking you from SP2 to SP3 the hard way. However, there still will be updates that were added after SP3, so it's not a total cure. StuRat (talk) 19:23, 19 December 2012 (UTC)

ADVISORY! As of October of this year, microsoft no longer supports Windows XP. It may be a great time to consider upgrading to Windows 7 (avoid 8). Phearson (talk) 00:59, 20 December 2012 (UTC)

Success of object oriented programming paradigm

I understand that it's easier to develop OO programs and work in a team and encapsulation, than to work with an imperative programming paradigm, but why isn't the function paradigm not more successful? Or the logical paradigm? OsmanRF34 (talk) 18:23, 19 December 2012 (UTC)