Wikipedia:Reference desk/Archives/Computing/2009 August 10

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August 10

Mac OS X under Ubuntu via virtualization

Does anyone know how to run Mac OS X in a virtual machine with Ubuntu as its host? Most VM software available seems to have no support for Mac OS X. --Belchman (talk) 00:24, 10 August 2009 (UTC)

I've had some success running it with qemu (at least it got through the installation, unlike VirtualBox), and there are reports of success using VMWare. But either way support will not be complete since OS X isn't meant to run on PC's. --antilived^{T | C | G} 03:39, 10 August 2009 (UTC)

Additionally, the OS X EULA specifically forbids virtualization of OS X on anything other than OS X. Whether that is legally enforceable, I don't know, but I wouldn't be surprised if that aspect of it was somewhat related to why these virtualization programs aren't really trying to get it to work. Apple has filed at least one lawsuit relating to this sort of thing that is currently pending. (OS X can run on PCs, with some work. See Hackintosh. There are EULA-related issues.) --98.217.14.211 (talk) 15:41, 10 August 2009 (UTC)

wireless laptops interfering with eachother

I currently bought a new router, only to find that when i try to access the internet from more than one computer, the internet for every computer gets disconnected (example I am on laptop 1, try to connect on laptop 2, both get disconnected from the internet) is there a way to stop this from happening? I am using a motorola modem and a linksys router, model number wrt110. If anoyone has any information that can help me stop my computers from interfering with eachother, I would greatly appreciate it. —Preceding unsigned comment added by Pianoman880 (talk • contribs) 00:50, 10 August 2009 (UTC)

What does your IP assignment setup look like (LAN side)? Off the top of my head, I would try hard resetting your router by holding down the "reset" button for 15 seconds and trying stated scenario again. --74.79.174.192 (talk) 02:20, 11 August 2009 (UTC)

There is a setting inside Linksys routers that limits the number of people connected to the router at one time. Click here: http://192.168.1.1/. The password is admin. On the home page, there's a setting for the "Maximum Number of DHCP Users." Check that.--IndexOutOfBounds (talk) 03:42, 11 August 2009 (UTC)

Washed a Micro SD adapter. Am I screwed?

My phone has a micro SD card in it, which it uses to store photos/etc. It came with an adapter, so I could plug the phone's SD card into the adapter (which would then fit into my computer's SD slot). Except it was in the goddamn washing machine. It wasn't in for very long, but there was detergent. No visible damage to the exterior of the card, no sudsing or anything like that. As soon as I got it out of the washer (halfway through the cycle) I rinsed the hell out of it with cold tap water. It's drying on my shelf. What's the deal? ZS 02:04, 10 August 2009 (UTC)

Probably ok . Make sure you let it dry completely (including any cavities). 83.100.250.79 (talk) 02:08, 10 August 2009 (UTC)

If it has a short in it because of contaminants (or some other horrible problem) and I plug it in, will it destroy my computer/microSD card/both? ZS 02:14, 10 August 2009 (UTC)

Tap water contains minerals that conduct electricity. Rinse it with distilled water, instead. If it is dry, it will not harm your computer. You can purchase distilled water in jugs at a grocery store.--IndexOutOfBounds (talk) 02:29, 10 August 2009 (UTC)

These adapters are cheap -- so cheap they are given away when you buy a new MicroSD card, that costs less than $10 these days. Consider whether it might be cheaper / safer to just replace the adapter. --FOo (talk) 06:02, 10 August 2009 (UTC)

Program structure - Derive all possible combinations of an arbitrary number of elements

I'm trying to derive all the possible combinations (not permutations because order doesn't matter) of an arbitrary number of elements. For example, if I have ABC then I want [A, B, C, AB, AC, BC, ABC]. I can generate the pairs, but how can I generate the second and third order combinations, let alone the n-th level combinations? The size of my input list will vary and I can't really predict its length ahead of time, so it has to be dynamically able to handle a list of any length.

My question is what program structure would be the usual, or what would work? I'm doing this in perl, but that shouldn't change the answer. Shadowjams (talk) 03:05, 10 August 2009 (UTC)

It sounds like you want the power set of a set of elements. Do you just need to find the number of possible sets? In that case it's 2ⁿ. If you actually want to list all the sets it's not really necessary to store them in memory; the binary numbers with up to n digits represent the sets by letting the kth digit represent whether the kth element is in the set or not. Rckrone (talk) 03:31, 10 August 2009 (UTC)

I am precomputing the number combinations in my program, although it's less than 2ⁿ because I throw out the single element and empty sets. 3 elements gives me 4 matches not 8 (AB AC BC ABC), or the sum [nC(n, n-1, ... 1)]. But I want to generate these pairs so I can run an operation on them. I'm comparing lists from each element for matches between the lists, and I want to do this for all combinations of elements. But aside from putting n loops for each n-th number of elements in the set (which wouldn't permit any number of elements), how can I do this?

I'll take a look at power sets here too... thanks. Shadowjams (talk) 03:58, 10 August 2009 (UTC)

I think I've got a workable answer. The power set is exactly what I'm working with.

I am going to map my elements to a binary number, run through each set of the powerset, and then run each selected element through my function. If anyone has any ideas of an easier way I'd like to hear it, but I think this will work. Thanks again. Shadowjams (talk) 04:38, 10 August 2009 (UTC)

There's two old discussions here

• http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Computing/2008_July_13#optimise maybe interesting but not in order - see below
• http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Computing/2008_July_10#Efficient_Programming

which might be of interest - these examples refer to numbers (ie the digits 0-9), but could easily be converted to characters.

The methods only generate the longest combinations - but it's easy to generate the shorter ones provided you use one of the method that generates the combinations in order eg ABC, ACB ,BAC ,BCA ,CAB ,CBA - it should be fairly easy to see how you can truncate these to varying extents to get the rest - when truncating by more than one field you need to skip the number of 'permutations' that are possible in the truncated part to avoid repeated results.

If this sounds interesting to you ask if you get stuck on the 'permuatations' part (it's simple but not necessarily obvious)

The non truncated case is also covered at Permutation#Numbering_permutations (mentioned in the above link, see links from this link for more.. may be of interest.)

If this is equivalent to a method you have already considered then ignore. Good luck.83.100.250.79 (talk) 20:39, 10 August 2009 (UTC)

Thanks. This is all pretty helpful. The one thing I didn't make clear is that I'm not just trying to just list all the combinations, but do something with those known combinations (each element is connected to a list I want to compare). The dirty hack way (and what I think I'm going to do) is make a table of combos, and use that table as the input into a function that will then go grab the appropriate lists, and do the comparison. I think this is what the previous question you referenced did.

What I can't figure out is a simpler way to do it. It feels like a long way around a simpler solution that is eluding me. I have nightmares of seeing a 3 line solution moments after I finish 50 lines of code to do the same thing. Shadowjams (talk) 21:46, 10 August 2009 (UTC)

I'm not sure I totally got the second part - for each combo eg ABC does this mean that A is pointing to a list, as is B and C - so you're actually combining lists? If that is what you are doing then you are doing it the sensible way.

Don't worry about the 50 lines (well not much) - better solutions always exist, and in my experience don't appear until you've written out the long one.. People publish there best stuff and don't tend to brag about the kludges. Better finished than not all. I think others (excluding a few lucky geniuses) will have had the same experience.83.100.250.79 (talk) 22:40, 10 August 2009 (UTC)

You can post your solution here, I imagine someone will be willing to look at it, assuming it's not too long, and has comments (or is simple enough the be obvious). Probably not really what the ref desk is for, but others do it.83.100.250.79 (talk) 22:57, 10 August 2009 (UTC)

Will Bluetooth prevent wear and tear on phone's jack?

My experience with MP3 players is that the headphone jack wears out first. I'm looking at buying a smart phone and using its MP3 functionality. Will a wireless stereo headset reduce or eliminate the wear and tear on the jack versus a corded one? NeonMerlin 08:44, 10 August 2009 (UTC)

Does a wireless headset use the jack socket??!! 83.100.250.79 (talk) 13:59, 10 August 2009 (UTC)

Molasses in January

Is there a problem with the new version of Firefox (3.5.2)? Wikipedia is slower to respond and it's especially troublesome on TCM, where I'm having trouble getting movie info to load. Clarityfiend (talk) 08:53, 10 August 2009 (UTC)

One identified problem is specified here -- "Microsoft.NET Assistant" is identified as a possible culprit. SunSw0rd (talk) 19:13, 10 August 2009 (UTC)

Check your Plug-ins and Extensions. Try loading it in safe mode and see if that goes any faster. Also, if the files it needs to load are splattered across your hard disk, you may see an improvement if you defragment the disk. 71.67.139.110 (talk) 17:34, 12 August 2009 (UTC)

iPhone vs BlackBerry for power users

What are the pros and cons of the iPhone compared to the BlackBerry for a user who wants to jailbreak and unlock the phone and run alternative firmware? NeonMerlin 11:39, 10 August 2009 (UTC)

I have no idea which of those two would be best - but have you considered an 'Android' phone? You can buy them as a 'developer' in a completely unlocked state [1] and have all of the source code for almost all of the software on it. Since anyone can be a developer - anyone can do this. These phones have generally similar functionality to iPhones and Blackberries but without any of the risks of having your phone 'bricked' if the manufacturer decides to get upset about 'jailbreakers'. You can even download and run an 'emulation' of the Android phone that runs on your PC so you can try it out before you buy. SteveBaker (talk) 02:07, 12 August 2009 (UTC)

GIS-like image rectification possible in Photoshop or Fireworks?

Hey all,

Years ago I was a GIS guy and did a lot of image rectification. I now find myself needing to slightly tweak a few map scans that weren't quite aligned. Because the scans overlap, I could have them perfectly rectified in only a few minutes.

However, I haven't used ArcGIS in years and really don't want to fire it up & relearn it for such a simple project. I'm thinking there's gotta be a way to do this in Photoshop by now? I have CS4...

Thanks in advance.213.146.164.143 (talk) 12:08, 10 August 2009 (UTC)

Record multiple inputs on a (vista) laptop - how?

I am currently using Audacity 1.33 (the beta version) and am trying to record more than 2 tracks at once. I have heard that on Apple Macs it is possible to set up some kind of software based ethereal mixer on the computer, and use this as an input for audacity - can this be done on vista? At all? I have also looked at adding a better sound card with more inputs, or a USB interface. I am using a laptop, and only have a small space (about 0.5cm x 5cm) for a sound card - can anyone tell me what this type is called? And can the 7.1 output soundcards be configured to record 5 or 6 tracks? Or are outputs strictly used for outputting? I ask because I have one line-in and two headphone jacks on my laptop, and if I could somehow (software?) configure the headphone jacks to act as line-ins, this would solve my problem - has anyone heard of anything like this?

Sorry for asking so many questions - any help is appreciated! —Preceding unsigned comment added by 89.241.117.47 (talk) 12:16, 10 August 2009 (UTC)

Output means output but you could try using USB microphones. Dmcq (talk) 15:39, 10 August 2009 (UTC)

Your options are more limited with a laptop, but you can try to find an external USB soundcard which can do multi-track acquisitions. Nimur (talk) 16:38, 10 August 2009 (UTC)

I agree that USB devices are probably better for you, but you also asked for the name of the "internal" card type - it seems to fit the description of PC Card. Jørgen (talk) 21:27, 10 August 2009 (UTC)

Google tools

Is there a Google tool for searching my own media - including word documents, PDFs, and all? I'd also like to add tags to videos and pictures to make them searchable. Basically, I want Google limited to my computer, but I want to customize the code to optimize it specifically for my needs. -- kainaw™ 18:15, 10 August 2009 (UTC)

There's Google Desktop Search for Windows, Mac, and Linux. For companies, who want to extend this index-my-stuff approach to a private network, there's Google Search Appliance]. -- Finlay McWalter • Talk 18:29, 10 August 2009 (UTC)

Thanks. Google Search Appliance is what I was looking for and all my searching kept coming up with Google Desktop Search. -- kainaw™ 18:31, 10 August 2009 (UTC)

GSA is much more sophisticated (it's really much of google's index and search capability), whereas GDS is very basic. Because it's a (tamper-evident, I believe) hardware device, they feel more confident about putting some of their fancier search software in there. But then GSA is (reportedly) seriously expensive. -- Finlay McWalter • Talk 18:34, 10 August 2009 (UTC)

Google Mini starts at £2400 (~$3960). It's certainly not intended for home users. — Matt Eason ^{(Talk • Contribs)} 20:03, 11 August 2009 (UTC)

Problem with iTunes + QuickTime on XP

I'm trying to install iTunes 8 on XP, but I can't get it to work. At the end of the iTunes + QuickTime install, it said "The installation of QuickTime did not complete successfully. iTunes requires QuickTime" and "The installer encountered errors before iTunes could be configured." When I tried to use Apple's standalone QuickTime 7 installer, it said "The installer encountered errors before the requested operations for QuickTime could be completed." Then I removed QuickTime from the computer with Windows Install Clean Up and tried the whole thing again. I finally got iTunes and QuickTime to install successfully, but when I try to open iTunes, it says "Some of your QuickTime software is out of date. You can fix this by updating to the latest version." I keep going back to the QuickTime 7 download and clicking on "repair", and it tells me that it's installed successfully, but iTunes keeps telling me that QuickTime doesn't work. What do I need to do? --Lazar Taxon (talk) 21:23, 10 August 2009 (UTC)

Are you looking to get iTunes or Quicktime to function? QuickTime Alternative is a free software codec which will let you decode QuickTime .MOV files, without installing iTunes or QuickTime. This will probably not help at all with regards to iTunes, though. Nimur (talk) 21:27, 10 August 2009 (UTC)

I'm only concerned with getting iTunes to work. --Lazar Taxon (talk) 21:50, 10 August 2009 (UTC)

It sounds like you need to update rather than repair quicktime - try looking for an update button on quicktime, or go to quicktime help and search for "update" - quicktime usually searches for updates on start up - so I recommend restarting the computer, and waiting a bit so quicktime can download updates. (Then hopefully it should be up to date and itunes will work)83.100.250.79 (talk) 21:31, 10 August 2009 (UTC)

Specifically: open quicktime, select edit , preferences , quicktime preferences then select the update tab (select automatically update if it isn't already is a good idea) then press "update"

That hopefully should fix it.83.100.250.79 (talk) 21:39, 10 August 2009 (UTC)

It's worse than that - I can't even get the QuickTime Player to open. When I try to open it, it says "Some of your QuickTime software is out of date. You can fix this problem by updating to the latest version." I proceed to press "Do it now", and then I get an error message saying "QuickTime is not properly installed. Please reinstall QuickTime." --Lazar Taxon (talk) 21:57, 10 August 2009 (UTC)

You've already tried uninstalling? erm. In "add and remove programs" - uninstall all apple software - there should be quicktime, itunes and something called "apple update". Then restart. And install just quicktime and see if it works. If that doesn't work or you've already tried I'd suggest restoring to a point (use System Restore) before you started with apple and try again.

I don't use itunes but I've installed quicktime into XP quite a few times without a hitch.

There's some advice here [2] which suggests using http://support.microsoft.com/default.aspx?scid=kb;en-us;290301

Assuming you manage to save the installer file to your hard disk I can't think of anything else obvious to go wrong.83.100.250.79 (talk) 22:32, 10 August 2009 (UTC)

If not fixed then maybe list software you're using -eg browser, firewall, anything on top of standard XP, and hope someone else spots the problem.83.100.250.79 (talk) 22:54, 10 August 2009 (UTC)

Do you use AVG Anti-virus? A little while back it was mistakenly targeting iTunes and Quicktime, and completely breaking them. I don't know if that has been resolved yet. —Akrabbim^talk 12:38, 11 August 2009 (UTC)

windows task scheduler

Hi everyone, Does anybody know anything about windows task scheduler? I have set the task scheduler to start a program at a specific time but I would like this program to close itself at a different time. I can not work out how to set the task manager to close programs, does anyone know much about task scheduler? or can recommend a completely different free task scheduler of a different sort. —Preceding unsigned comment added by 219.90.149.102 (talk) 23:14, 10 August 2009 (UTC)

I've used Task Scheduler probably a dozen times and have never known that it had the ability to close a program — just launch a program. Tempshill (talk) 23:36, 10 August 2009 (UTC)

If you are using Windows XP, you might try experimenting with the taskkill command. For example, I created a text file with the following line

taskkill /im notepad.exe

and saved the file as "close-notepad.cmd". Now I can set up a Scheduled Task to run the close-notepad.cmd file.--Bavi H (talk) 01:36, 11 August 2009 (UTC)

There's an option in the "Settings" tab for the task to "Stop the task if it runs for (some amount of time)". AndrewWTaylor (talk) 09:12, 11 August 2009 (UTC)

the case of the intermittent Option key

I use a Mac. Sometimes as I'm writing here, I find that the Option key has stopped working, at least in this here editing panel. (Typically I notice it when I'm trying to make the dash in my signature.) And then a little while later it may come back, as it did a little while ago. Do y'all know an obvious reason for this phenomenon? —Tamfang (talk) 23:47, 10 August 2009 (UTC)

Have you tried tapping the Option key, hard, a few times in a row? It may be a hardware issue. Tempshill (talk) 01:46, 11 August 2009 (UTC)

I believe it affects both Option keys at once. —Tamfang (talk) 03:10, 12 August 2009 (UTC)

Try refreshing the page, sometimes things just get stuck. --Kraftlos (Talk | Contrib) 11:30, 11 August 2009 (UTC)

Huh? The failure lasts through more than one edit session. —Tamfang (talk) 03:10, 12 August 2009 (UTC)