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April 30

Dual opamps

Hello Sirs! Could you please enlighten me a bit on a few things here - I have a preamp that uses dip socketed mono opamps per each channel (lefr right - two opamps) that is they are mono opamps per each channel , so my concern is , is it ok to put a dual to mono opamp in there although it only needs one of them per channel, will the other just be idling or something without breaking anything or creating any problems? Thanks !! — Preceding unsigned comment added by 77.35.7.130 (talk) 12:29, 30 April 2013 (UTC)

It is a good idea to properly terminate or bias unused leads as per the spec sheet. Here [1] is a reasonable example of terminating an unused op amp. Dmcq (talk) 17:21, 30 April 2013 (UTC)

GameCube/Wii regional lockout

Hello. So I know this: Both the Wii and Gamecube are regionally locked, There exists a "Freeloader" lockout disabling apparatus for the GC, The Wii is backwards compatible with all GC games and most of its accessories. So is it possible to play a Japanese GC game on a North American Wii, using the freeloader? If so, is it restricted to certain firmware versions or earlier models? Thanks, --JadeGuardian (talk) 18:54, 30 April 2013 (UTC)

The Wii is notorious for not supporting mods (and the official Game Boy Player - really too bad!) for the GC. Providing a link to the exploit you are interested in could help, but all I can say is it would probably be a better idea to check out a modchip for your Wii that would unlock it. As for the firmware, I don't think the Wii firmware has been updated in a while so if you are getting a new modchip then it will probably work (remember to always read the infomation for any hack carefully before you buy/download it!!! This applies to any electronics!), but for the GC mod I don't know. My guess would be that it would only work on very old versions of the Wii firmware. There are ways to downgrade, but getting an exploit for the Wii rather than the GC would be a lot less complicated and (In my opinion) safer. Hope that helps! --Yellow1996 (talk) 23:41, 30 April 2013 (UTC)

I don't have an answer on if it allows getting around regions, but a modchip is no longer required for the Wii. Everything can be done through an SD card and the system software. There are GC loaders for modded Wiis, but I haven't researched region issues. It does allow playing out-of-region Wii games. 38.111.64.107 (talk) 13:59, 1 May 2013 (UTC)

Oh, okay. I wasn't aware of that, thanks 38.111.64.107! (I've been a little out of the hacking loop...) :) In that case I guess you'll need to find one of those SD-based hacks that does support region-free GC loading, if such a thing exists (probably does.) If not, the modchip idea would probably still work - I believe some of the newer ones are very easy to install, too. --Yellow1996 (talk) 01:49, 2 May 2013 (UTC)

Kill javascript running in Firefox

Can you kill js (without killing Firefox) specifically? (This is not about disabling it). OsmanRF34 (talk) 19:59, 30 April 2013 (UTC)

You can use some ad blocker to prevent a particular js file from loading. Ruslik_Zero 02:37, 1 May 2013 (UTC)

You can kill firefox, re-start it and allow it to restore your session, but disable JS in-between. :) ¦ Reisio (talk) 03:12, 1 May 2013 (UTC)

JS doesn't run as as a separate process from Firefox. The closest thing you can do is disable javascript from specific sources, and reload the page. NoScript does this. --Wirbelwind(ヴィルヴェルヴィント) 06:55, 1 May 2013 (UTC)

It is possible with windows because of WINAPI.Firefox (checked dor 3.6) use(d)? some basic javascipt part of windows API.You might not find a separate thread for each javasript program.

In UNIX all is files in Windows / OS/2, all is handles (more than files with unix). There is probably a directory that group all related javacript API actions.Then you can can create a basic C/C++ program for closing the handles you want. I think the WINAPI provides functions to deals with handles, so it should be easy.

The handles created by WINAPI might not be documented so you may have to look in internals windows functionement.

You may crash the process but don't forget that most of the time, firefox open a pop-up prompting killing the .js app or let it runing.You need to use this only if it doesn't open.2A02:8422:1191:6E00:56E6:FCFF:FEDB:2BBA (talk) 13:10, 1 May 2013 (UTC)

Updating SSD firmware

Is there any way to update a drive's firmware if I can't install it into a computer? A Macbook Air doesn't have any native SATA ports. And I can't update firmware if I place the SSD into a external USB 3.0 enclosure, correct? --Navstar (talk) 22:09, 30 April 2013 (UTC)

Yes, with a disk enclosure you can do it. OsmanRF34 (talk) 22:22, 30 April 2013 (UTC)

May 1

Alcohol abuse and my netbook

A terrible thing happened: I spilled some delicious Corsendonk Christmas beer on my netbook, a Toshiba NB 505. (Trout me for it.) Now my space bar is stuck. I've figured out how to get the whole keyboard off, but that doesn't allow me to clean under the bar. On this netbook, do those keys pop off like on a regular keyboard? Even my previous laptop allowed that--and what I mean is that I could put it back on afterward. With this thing I don't know if they pop off and back on. I'll take any advice y'all have to offer. Thanks! Drmies (talk) 14:00, 1 May 2013 (UTC)

That should teach you a lesson, if drinking, do not type. Anyway, I've never seen a key that wouldn't pop when pulled. but don't do it from the side, just pull two points along the bar. Otherwise a vacuum cleaner or a compressed air can can be of use here. OsmanRF34 (talk) 14:36, 1 May 2013 (UTC)

On spacebars (and some larger keys), there is a stiff piece of wire connecting the outside edges of the key together - the ends of the wire are attached to hooks on the underside of the key, and there are pivots on the PCB, attached near the middle of the wire. Slide the wire to the one side to unhook it from that end, and then slide to the other side to unhook it from the other end of the key. CS Miller (talk) 15:55, 1 May 2013 (UTC)

Right, it's not exactly like other keys. For more detailed information, this is one of the rare cases when youtube is a better source than wikipedia. Try searching for "how to remove the spacebar" there. OsmanRF34 (talk) 16:37, 1 May 2013 (UTC)

Never done this before on a Toshiba NB 505 but look at this - it roughly follows what has worked for me in the past.[2] By about 3 minutes in, it shows you how to get the keyboard out. A simple agitated wash in a bowlful of weak detergent (20 mins minimum) and a very good rinse off on distilled or de- mineralized water followed by a couple of days to dry off in a warm airing cupboard may be all you need. If the laptop has been in use for a while you might like to refer to this on how to get rid of all the accumulated crud.[3] You have nothing to loose by taking the latter route first because it will be a good learning exercise, an further rub it in, that from now on you must be more responsible when handling alcohol. The exercise may come in useful for when your niece spills Florida Orange juices on her keyboard. Keyboards are not connoisseurs. Icky liquid is all the same to them, what ever the liquid's provenance.Aspro (talk) 16:10, 1 May 2013 (UTC)

I watched that video yesterday, very helpful, and removed the keyboard though I stopped short of pulling that connector off, hoping I could deal with the one key individually. I'll try again to see if I can snap the one key off, and if that doesn't work I'm cleaning the whole keyboard. Thank you all for your help! Drmies (talk) 17:36, 1 May 2013 (UTC)

And, if the space bar just never works again no matter what you do, there's always an external keyboard. You can get a light and small keyboard that won't make your laptop all that much less portable. StuRat (talk) 19:18, 1 May 2013 (UTC)

• I managed to pry off the space bar, cleaned the metal connections, and it's clicking perfectly. Thank you all so much! Drmies (talk) 15:18, 2 May 2013 (UTC)

Resolved

Windows Media Player not updating metadata properly?

I borrowed a copy of Pixies' album "Surfer Rosa" from a friend. This is all very fine and good, and it even came with the tracks from their debut EP Come on Pilgrim. I decided, however, to split the albums into two using Windows Explorer, feeling it would be more organised to keep the albums separate than as one whole. I edited the metadata as is standard for Windows Explorer on Windows 7, but when I opened Windows Media Player I found that it was frustratingly refusing the accept that the two albums were now separate entities. What can I do to change this behaviour, or am I stuck? --Editor510 ^{drop us a line, mate} 16:34, 1 May 2013 (UTC)

Okay, now WMP is just claiming that the files don't exist altogether and actually offered to remove my entire library??? What the hell is going on? --Editor510 ^{drop us a line, mate} 16:37, 1 May 2013 (UTC)

It's also refusing to delete said files, or play them. Jesus Christ I hate this program. --Editor510 ^{drop us a line, mate} 16:38, 1 May 2013 (UTC)

VLC; GNU/Linux ¦ Reisio (talk) 17:10, 1 May 2013 (UTC)

Did you remove the old entries from the library and re-add them? If their file path is even slightly different from what it once was, it will no longer find the file and needs to be re-added. -- 143.85.199.242 (talk) 19:16, 1 May 2013 (UTC)

GPS-traces or elevations for European Highways

I investigates hybrid vehicles of different kinds and would like to calculate battery usage on different routes. It would be very useful to be able to get the elevation profiles and slopes of major highways in Europe such as E45 or E62. I am sure very many people have recorded such GPS-traces, some of them can be found on [4] but they only seem to be publicized in chronological order with no way to find a trace of a specific road. Do you know how/where to find this type of information? An other way would be to use the google maps API and do something like: [5] or [6] but the terms of use for google map data seems to be rather confusing at best regarding this type of use and it would probably require some programming to extract it as a text file table or similar from the API, the simulations will then be done in Matlab or Python. Do you know any web service that provides GPS-traces or orher sources of altiude-profiles of Highways? Gr8xoz (talk) 19:25, 1 May 2013 (UTC)

There's a rough manual way you can do this in Google Earth:

• add->path, then click at various points along the route
• in the "places" section in the left bar, where the new path you created is shown, right-click on it and click "elevation profile" in the context menu that pops up.

It's very detailed (it's not just the altitudes at the points you clicked, but at all those on the line between those points). But I don't know how to save that profile (bar taking a screenshot) or how to export it (looking at the KML file you get if you export the path, the Z coords are all 0, which I take to mean an offset from the prevailing ground level at that lat/long). -- Finlay McWalterჷTalk 20:08, 1 May 2013 (UTC)

Beyond that, I'd ask at the OpenStreetMap forum. They do have actual GPS traces, but really you don't want them - OSM weaves a tapestry of traces into a coherent mesh, and what you want is to be able to extract the altitudes for a given road or set of roads. OSM too has an API (here) - folks at the forum there should be able to advise you on how to proceed with it. -- Finlay McWalterჷTalk 20:12, 1 May 2013 (UTC)

The problem with OSM in this application as far as I understand is that the map itself is only 2D (With a few exceptions [7]) while the original traces often have altitude. This [8] google Summer of Code project seems to be an attempt to get the data I need by combining OSM routes with NASA radar measurements [9] but it does not seem to have any server online, maybe I could install my own but it seems to be a lot of work.

Gr8xoz (talk) 21:49, 1 May 2013 (UTC)

Microsoft Word 2007 Problem

At my place of work, Microsoft Word 2007 seems to be having a problem. For example, when trying to make a hyperlink, you would normally press Enter after creating one; it would turn blue and become clickable, correct? In my case, it becomes something that looks like this:

{HYPERLINK "mailto:fakeaddress@somemail.com"}

Other hyperlinks do the same thing, such as:

{HYPERLINK \1 "MEETING"} {HYPERLINK \1 "DATE"}  {HYPERLINK \1 "ACTION_ITEMS"} 

Page numbers appear as:

{ PAGE \* MERGEFORMAT }

Can anyone help me return Word to normal operation? -- 143.85.199.242 (talk) 22:00, 1 May 2013 (UTC)

I think you have "show field codes" turned on. info -- Finlay McWalterჷTalk 22:20, 1 May 2013 (UTC)

That was it! Thank you! -- 143.85.199.242 (talk) 22:59, 1 May 2013 (UTC)

Resolved

May 2

Strange audio/video stuttering problems

Hi all. I've got a strong computer. An Intel i7 CPU and GTX 460M GPU seem pretty strong to me. And they often perform their duties admirably well. But they seem to trip up on really small things much of the time.

If I'm watching a video, the video may pause for a fraction of a second (with the audio still running normally), then skip ahead to where it would be if it hadn't paused at all. The intervening frames are either dropped, or played back very sped up. For example, if the video featured someone walking across the room, they would stop in place and then either teleport to the other side, or scurry over, their legs moving in a flurry. This can happen when watching any video online, and is particularly noticeable when watching videos on iTunes. However, I can't find any sort of common factor between occurrences. Sometimes it works just fine, other times it doesn't. One thing I'll mention is that I almost never see this problem happen with Crunchyroll's online video player, if that helps.

Both video and audio stutter when playing Minecraft, to an unacceptable degree. However, this only happens when the sound is on. For example, let's say I start the game up, and am standing where I last left off. Upon the first step I take, the game will freeze for about a second, and then the player character will slowly move forward, and the sound of walking on the surface I'm on plays. This freezing happens with every "new" sound that the game has to play back. That is to say, if I haven't walked on grass since starting the game, the first time I walk on grass will be rife with stuttering gamplay as each walking-on-grass sound is played for the first time. However, it still has a tendency to happen, to a lesser degree, with any sound. The game still seems to be running when it's frozen; time-sensitive processes will continue. For instance, Creepers are enemies that explode when you stand near them for too long. Several times I've run up to a Creeper and had the game freeze for a moment from either the sound of the Creeper starting to hiss, or me attacking the Creeper, or both. When the game unfreezes, the Creeper explodes, essentially making it instantly detonate when I try to attack it. Turning sound off in Minecraft's options mostly eliminates this problem, but I would like the sound back.

Left 4 Dead 2 has problems as well, but they manifest in a different way. "New" sounds that haven't been played before have a delay for when they should play. For example, if I pick up a shotgun and fire it, the first time I fire it will have the sound of its blast delayed for a second. It works normally for the rest of the game after that. This goes for all guns, grenade sound effects, and possibly others that I can't notice as well. This effect also manifests itself in the menu. When scrolling through menu options, the whole game stutters for a second if I scroll over something that has not been previously accessed. I can't move the cursor during that time, and the audio repeats a very short loop several times. For example, if the menu music had someone speaking in it, saying something like "Please include your system specs" and I scrolled over something in the middle of the sentence, I'd hear "Please include your clude your clude your clude your system specs." This happens to a lesser degree while playing BioShock.

I really don't know what to make of this. This is supposed to be a fairly strong computer, but it feels like its shoelaces have been tied together with these problems. I've tried updating my drivers through NVIDIA's Web site, but I feel like incidence of screen tearing during video playback only increased for a few weeks after doing so. What do you think could be the cause? What can I do to fix this?

Windows 7 Home Premium, Service Pack 1

Intel Core i7-2630QM

NVIDIA GeForce GTX 460M

Thanks for your time.--The Ninth Bright Shiner 02:49, 2 May 2013 (UTC)

(Oh, and one thing I forgot; timing for things spoken by the survivors in Left 4 Dead 2 can be pretty off. A survivor might make the relieved "ahhh" sound right before they actually take their pain pills. Speech might get cut off: instead of Ellis saying "That man is an American hero," he'll just say "That man is an American" and get cut off.--The Ninth Bright Shiner 02:54, 2 May 2013 (UTC))

I'm getting the impression that your worst problems are with audio. What sort of audio setup do you have on the system? (See Control Panel->Hardware and Sound->Sound->Manage Audio Devices, in case you have trouble finding it.) Looie496 (talk) 03:09, 2 May 2013 (UTC)

Conexant SmartAudio HD?--The Ninth Bright Shiner 03:34, 2 May 2013 (UTC)

Sounds a lot like a hard drive problem to me. Loading new sounds/assets into memory will freeze up the game since if waits on the (irregularly long) read, or the sound will play late and be cut off since it took too long to load. You should run a SMART diagnostic. 198.168.234.223 (talk) 19:28, 3 May 2013 (UTC)

I used Passmark's disk checkup. How do I interpret the data it gives me? Thanks for your help.--The Ninth Bright Shiner 02:50, 6 May 2013 (UTC)

Graphics with Java: Applets and Applications

I am trying to convert a java applet to a java application. I have done all the conversions i needed, including changing the content pane to a JFrame. However, it seems the paint method doesnt work. I'm not sure what im doing wrong, but im guessing applications deal with painting differently. Does anyone know what is wrong? If it is necessary, i am willing to post the source code. The main class still extends JApplet, which i wonder if its part of the problem or not.

Again, let me know if posting some source code is needed.

137.81.118.126 (talk) 05:56, 2 May 2013 (UTC)

Make sure you're adding children to the JFrame's contentPane, not to the JFrame itself, as shown in the JFrame javadoc page. While you can try to use JApplet inside a JFrame, without someone implementing all the stuff that an AppletContainer provides, all the utility methods in java.applet.Applet (e.g. getImage) don't work. Personally I'd recommend you don't use JApplet like that, and instead change your code to extend a JContainerJPanel instead. If you want to post your code for others' review, I'd recommend you post it at pastebin and only post the URL of that here; but make sure your code compiles with no warnings before you do that. -- Finlay McWalterჷTalk 07:01, 2 May 2013 (UTC)

I tried to change to extending JFrame JPanel, with no luck. The program unfortunately has a few classes if you are wanting to have it compile entirely. I will get to working on it. 137.81.118.126 (talk) 07:26, 2 May 2013 (UTC)

I sounds like you're trying with too complicated an example, and probably people won't be interested in helping you debug a whole application. It's much easier for people to help you if you can reduce your problem to a single class; often the practice of doing this will let you see the problem yourself. -- Finlay McWalterჷTalk 07:40, 2 May 2013 (UTC)

The source is all available now. I tried to make pretty decent comments noting the division between files. There are 5 classes, "Application", "Attractor", "Build", "Main", and "MouseListen".

http://pastebin.com/kkSj4zZJ

Edit: The only problem is within the painting of things. It wont involve digging into the "Build" class, for instance, which has nothing to do with the issue.

Edit 2: If the painting of things is fixed, instead of a gray empty area on the left, there should be a purple background with a gray dot you can drag around.

137.81.118.126 (talk) 07:42, 2 May 2013 (UTC)

You've gotten into a muddle because Application extends JFrame, but then in its init you create a new JFrame. You never display the Application, only the new-ed one, and your paint methods are on the frame you never display. So there's no painting. As a hack, you can see this by changing the line

        Frame frame = new JFrame("Attractors v2.0");

with

  
        JFrame frame = this;

and you get repainting. But really you should change Application.init() to be the constructor of the Application class. -- Finlay McWalterჷTalk 14:51, 2 May 2013 (UTC)

Incidentally, painting on the same JFrame that you're hosting widgets on is, while it works, confusing. You'd be much better off created another widget (e.g. AttractorCanvas extends JPanel), adding it to the JFrame (BorderLayout.West) and having all the painting in there). Right now your Application.paint() call applies for the whole Application, which means it can paint over the controls on the left (if the clip is so set). Another incidental thing (I know you didn't ask for a full code review, but since I'm here...) your paint method gets much more readable if you use an iterator:

    @Override
    public void paint(Graphics g) {
	g.setColor(bgCol);
        g.fillRect(0, 0, 500, 500);

        for(Attractor item: attArr){
            int d = item.getR()*2;
            int x = item.getX();
            int y = item.getY();

            g.setColor(Color.LIGHT_GRAY);
            g.fillOval(x, y, d, d);
            g.setColor(Color.DARK_GRAY);
            g.drawOval(x, y, d, d);
        }
    }

-- Finlay McWalterჷTalk 15:36, 2 May 2013 (UTC)

Finlay, your analysis of my program has been most helpful! I have made most of your changes, except for having the separate drawing pane, and reorganizing the paint method. I deleted the frame that is unneeded, and anywhere i used to reference "frame" i use "this" now. Ex: this.setSize(960,510); ..........

The images now show properly, but when i use things from the MouseListen class, they dont update the screen appropriately. The MouseListen class takes in Application by reference and calls its "repaint" method. Again perhaps im not familiar enough with applications as opposed to applets, but this appears to do nothing. How could i fix this issue? 137.81.118.126 (talk) 18:52, 2 May 2013 (UTC)

It's nothing to do with applications vs applets; you're either not receiving the events because you've not listened on the correct control, or you're sending repaints to the wrong control. Your code is overcomplicated and distributes responsibility for control in a weird way. You should refactor it, with a single JPanel responsible for storing the Attractors, rendering them on itself, and handling its own painting and repainting. -- Finlay McWalterჷTalk 20:16, 2 May 2013 (UTC)

..a decent point. I will attempt to merge MouseListener class with the Application class.

Edit: I dont think this is possible because MouseListener extends MouseInputAdapter, and my application already extends JFrame. Java cant allow one class to extend two other classes. Not sure what to do but i see your point that power over the application is spread out.

137.81.118.126 (talk) 20:29, 2 May 2013 (UTC)

I have had a look at debugging and all the paint methods work perfectly, there is just a different bug, and im confident i can fix it. Thank you for your help!

Resolved

137.81.118.126 (talk) 22:31, 2 May 2013 (UTC)

is there software that can determine a person's race

from their name? — Preceding unsigned comment added by 119.74.102.57 (talk) 09:14, 2 May 2013 (UTC)

Obviously not, since anyone can change their name to anything they like. Even if you assume the input is a person's birth name, the most that could be achieved is a probabilistic guess at their parent's ethnic and cultural background (and note that this is not the same as their race) e.g. the parents of Dermot O'Leary are probably Irish. Gandalf61 (talk) 09:28, 2 May 2013 (UTC)

As just a case in point, compare George Clinton and George Clinton. --Mr.98 (talk) 15:44, 2 May 2013 (UTC)

Race isn't something that can be 'determined' at all. It is a social construct - an arbitrary subdivision of humanity based on local cultural distinctions, rather than anything more concrete. One only has to look at the almighty tangles that apartheid-era South Africa got into trying determine who was 'what' to see that it is impossible to define objectively. It is also worth noting that those who have attempted to justify the subdivision of humanity into 'scientifically defined' races have singularly failed to even agree amongst themselves as to how many there are, never mind how you determine membership. AndyTheGrump (talk) 16:06, 2 May 2013 (UTC)

Just because something can't be neatly categorized doesn't mean it's arbitrary or meaningless. You might as well say languages are arbitrary social constructs (why are Swedish and Danish separate but not High German and Vorarlbergerisch???). We certainly can't agree on how many languages there are either. That doesn't make the concept any less meaningful or useful. That being said - yes, the original poster's question is certainly impossible. -Elmer Clark (talk) 22:45, 2 May 2013 (UTC)

You misunderstand. Genetically, you cannot group humanity into more than one subspecies (race). All humans are the same race -- Homo sapiens sapiens. Homo is the genus; sapiens is the species, and sapiens is the race. We try to group humans into races using skin color and facial characteristics, but this method fails when you realize that people with the same skin color vary more genetically among themselves than between any other grouping. Humans are remarkably similar to each other genetically compared to other animal species. The other human races died out tens of thousands of years ago.—Best Dog Ever (talk) 05:49, 4 May 2013 (UTC)

I once met an Asian man named Laquisha Brown and asked him how he got that name. He explained that he was waiting in line at immigration, the immigration officer asked the woman in front of him her name, she said "Laquisha Brown", and the immigration official wrote it down on her papers. When it was his turn and they asked his name, he said Sam Ting, so they wrote down Laquisha Brown on his forms too. :-) StuRat (talk) 18:18, 2 May 2013 (UTC)

Two can play at that game, my friend!

I once met a German man named Sean Ferguson and asked him how he got that name. He explained that he had been advised to give the immigration officer a good American name, like John Smith, so he patiently stood in line repeating "John Smith, John Smith", but when he got to the front of the line he was so nervous it slipped his mind, and he said "Ach! Ich habe schon vergessen!" and Sean Ferguson he became.Gzuckier (talk) 21:22, 3 May 2013 (UTC)

Bonus: You ever wonder if Ang Lee got his name because he became irritated waiting in line at immigration and told the officer he was angry? Gzuckier (talk) 21:24, 3 May 2013 (UTC)

Perhaps to give a more useful answer to this, the study of where names come from is a serious one. It has its own name, but I can't recall it right now. (Google isn't helping me much.) While, as pointed out above, some names are no help at all in determining someone's ancestry, many still are. Mine happens to be. It's a name typical of where my predecessors came from. Books have been written on this topic. Part of determining this is a fairly mechanical process. I can imagine the contents of such books being turned into software that could at least act as a potential guide to discovering someone's ancestry, but I've never heard of any. (I won't use the word race here. Again, for many reasons including some outlined above, it's inappropriate.) HiLo48 (talk) 03:50, 4 May 2013 (UTC)

Onomastics? Asmrulz (talk) 21:59, 6 May 2013 (UTC)

Friend of mine tells of having an Asian-American roommate in college, who often spoke of "Grandmother Wong" who ruled the family with an iron fist. Anyway, eventually came a visit to roommate's home over vacation, and Grandmother Wong turned out to be an Italian woman who had married Grandfather-to-be Wong many years ago. Gzuckier (talk) 04:37, 5 May 2013 (UTC)

Maybe the OPs question has a simpler answer. If the name is a unique key into a database (or there is secondary information), and that database stores a race attribute (no matter how scientifically valid or invalid that assignment) for each data set, then yes, there is such software. --Stephan Schulz (talk) 22:39, 7 May 2013 (UTC)

Making a single page of a section landscape in Word

I'm using Microsoft word for a document with a set of drawings at the end, which are numbered separately from the main pages (in the form X/Y, {Page}/{SectionPages} ). I want to make a single page of the drawings landscape, but the only way I know how to do that is by making a new section for the landscape page, so {sectionpages} doesn't work any more. Is there any way to either:

• Change {sectionpages} so that it shows the total of the last (n) sections (i.e. to include the portrait and landscape sections)
• make a single page landscape without changing section?

Unfortunately, the landscape part has to be in the middle of the drawings, and I'm likely to be editing either side of it, so I can't even just fudge it for all but the last section, and then use ={sectionpages}+Z for the final section. many thanks MChesterMC (talk) 14:50, 2 May 2013 (UTC)

Follow up on this, I've worked around it my using {= {NUMPAGES} - {PAGEREF Bookmark}}, with the bookmark set at the last page of the previous section. It only works because I have only two sections total (the main document and the drawings), but it's good enough! A better solution would still be appreciated, since if this document gets amended and I have to insert more pages (which will go in as e.g. 5, 5a, 5b, 6) it will break the formatting again MChesterMC (talk) 09:32, 3 May 2013 (UTC)

"SecuROM" in The Sims 2/3

I recently bought The Sims 2 Deluxe the The Sims 3 Deluxe, after a long time with only The Sims 1 (Complete Collection). Only about purchasing the games, but not installing them yet, I read about the games and learned that they included something called "SecuROM" which a lot of people find horrible. In my research, SecuROM could cause problems to your PC in some cases. Why would Maxis/Electronic Arts knowingly release a game with such technology, and should I be worried about installing it? Thanks! -- 143.85.199.242 (talk) 16:58, 2 May 2013 (UTC)

Reading our SecuROM article will probably give you more information than any answer here could. Looie496 (talk) 17:05, 2 May 2013 (UTC)

I actually did read Wikipedia's article; apparently there are multiple versions, some with differing bad characteristics. I'm looking for advice on what the SecuROM included with Sims 2 Deluxe and Sims 3 Deluxe would do to my PC, if anything. -- 143.85.199.242 (talk) 22:58, 2 May 2013 (UTC)

I've installed the Sims 3 before and I didn't notice any kind of DRM (other than needing the DVD to play) but it's been a while, and I didn't look very hard to see what it did to the cpu. Shadowjams (talk) 22:44, 3 May 2013 (UTC)

I've used the electronic SOED, which install SecuROM (presumably v7.1, because it creates files names securom_v7_01.* - which may be quite old; the disk was published in 2007),and I've not had any problems with it on either 32-bit Windows XP Pro or 64-bit Windows 7. There is no online authentication or registration. The DVD needs to be inserted the first time the program is run per-user on any given PC. Naturally I've only ever had it installed on one PC at a time :-) Mitch Ames (talk) 12:41, 6 May 2013 (UTC)

Pokemon, 3rd gen. celibi

Hello. So I've heard that the only way to obtain Celibi without cheating is to transfer it from the Japanese Pokemon Colosseum pre-order bonus disk. Can you load this Japanese monster to the American Ruby, Sapphire, FR, LG or Emerald? And as a bonus, how rare are these disks and about how much do they go for? --JadeGuardian (talk) 19:29, 2 May 2013 (UTC)

Uhh, hello? --JadeGuardian (talk) 21:10, 2 May 2013 (UTC)

You allowed two minutes between when you asked your question and when you posted about your impatience. There aren't Pokemon experts manning this desk 24/7. If anyone can supply the answer, they may in fact do that but getting pissy with the readers here will not really encourage them to assist you. That said, you may be able to get an answer more quickly on a specialized Pokemon forum or message board. To me, your question seems rather obscure and specific, so a specialized forum may be your best bet. Dismas|^(talk) 21:18, 2 May 2013 (UTC)

Actually, I posted this much earlier, but came back because I forgot to add the signature. --JadeGuardian (talk) 21:22, 2 May 2013 (UTC)

Unfortunately, you can't. The Japanese disk only works with Japanese game carts (according to Bulbapedia; I haven't done it myself - I've been an AR user since the beginning! :) ) As for the price, eBay states a price window of $25-$75 but that is for both versions together (English and Japanese) - if you are interested in a Jirachi or are willing to purchase a Japanese version of one of the games, that is! --Yellow1996 (talk) 23:56, 2 May 2013 (UTC)

Checking my mac's memory usage

 Model Name:	             iMac
 Model Identifier:	        iMac11,3
 Processor Name:	        Intel Core i5
 Processor Speed:	        2.8 GHz
 Number Of Processors:	        1
 Total Number Of Cores:         4
 L2 Cache (per core):	        256 KB
 L3 Cache:	                8 MB
 Memory:	                8 GB
 Processor Interconnect Speed:	4.8 GT/s
 Boot ROM Version:	        IM112.0057.B00
 SMC Version (system):	        1.59f2

Is there a way to check what percentage of my computer's memory is filled up? I have tried system profile but it just tells me how much memory I have in total, per above, 8 GB. Also, can anyone tell me how much memory I can use up without it significantly affecting my performance?--108.54.26.164 (talk) 22:48, 2 May 2013 (UTC)

Try the "Activity Monitor" (Applications > Utilities). The "system memory" tab shows you lots of RAM information. Green is totally free, blue is "recently used" which means it is technically free but sometimes the OS doesn't free it up in a timely way (you can run the "purge" command in the Terminal to manually force it to free that up, if you're into that kind of thing), red is "used by really important processes" and yellow is "used by regular programs." More or less.

As for performance issues... basically if you drop down to levels where your machine needs RAM you don't have available, it will use virtual memory, aka hard drive space. This slows things down a lot because hard drive reads and writes are slow compared to RAM. Under the aforementioned "System memory" tab, look for the "swap used" item. If it is more than just a tiny amount, then you're running into performance issues based on not enough RAM free. Otherwise, your performance issues are probably not RAM related. --Mr.98 (talk) 00:23, 3 May 2013 (UTC)

Thanks Mr.98. It says "Swap used: 261.7 MB" Does that ring any alarm bells for you? I know you said if it's more than just a tiny amount..., but when we're talking about 8GB, is 261 a lot? Most of my memory is taken up with video storage btw. Maybe I should put a lot of it on an external drive (they're fairly cheap) and off the computer's hard drive?--108.54.26.164 (talk) 01:16, 3 May 2013 (UTC)

Blue is actually better described as "a good candidate for swapping out to disk": it's memory that a program has indicated it's using, but hasn't actually touched in a while. --Carnildo (talk) 02:55, 3 May 2013 (UTC)

Mmm, that's not really what Apple says about it. "This information is in RAM but it is not actively being used, it was recently used. For example, if you've been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. Inactive memory is available for use by another application, just like Free memory. However, if you open Mail before its Inactive memory is used by a different application, Mail will open quicker because its Inactive memory is converted to Active memory, instead of loading it from the slower drive."

As for swap... how much do you have in the "Page outs" category? My feeling is that a quarter of a gig of swap is kind of a lot. Not a ridiculous amount, but it indicates you are hitting your memory limits more often than one would expect to with that much RAM. As for your use of the hard drive space, it doesn't really matter to this question. Whether your hard drive is empty or full isn't what is at issue here. --Mr.98 (talk) 13:01, 3 May 2013 (UTC)

Page outs is listed as 1.79 GB. Maybe I have this happening because I sometimes download many videos at once, and that puts a strain on the system?--108.54.26.164 (talk) 12:54, 5 May 2013 (UTC)

On the accuracy of floating point

I have a program that must complete the operation 18abcd - 4b³d + b²c² - 4ac³ - 27a²d², where a = 10.648, b = 638.88, c = 12777.6, and d = 85184. Both Wolfram Alpha and Google's calculator confirm that the answer is 0, but the program returns 0.00390625, which skews all its other results. Why is this and/or how can I fix it? I've checked the syntax very thoroughly, and it isn't the problem. Pokajanje|Talk 23:01, 2 May 2013 (UTC)

see Floating point#Accuracy problems. If you know the answer is zero, why do you need to calculate it? AndyTheGrump (talk) 23:06, 2 May 2013 (UTC)

It's part of a function with the four arguments a, b, c, and d. I was testing it and discovered the flaw with those numbers, and I can't possibly make an exception for every case like this. Pokajanje|Talk 23:24, 2 May 2013 (UTC)

If you want exact results every time, you can't use floating point numbers. AndyTheGrump (talk) 23:33, 2 May 2013 (UTC)

If I can't use floating point numbers that will render the whole program useless. Pokajanje|Talk 23:37, 2 May 2013 (UTC)

Is it essential that you always get exact results? AndyTheGrump (talk) 23:42, 2 May 2013 (UTC)

Yes. Pokajanje|Talk 01:47, 3 May 2013 (UTC)

Then, as has been pointed out correctly, you cannot depend on floating point. Floating point math can introduce numerical error. You can learn very advanced theoretical mathematical techniques that reduce that error in general; and you can learn advanced practical techniques that reduce the error for common applications (for example, by reading Numerical Recipes, most of which is available for no cost online at nr.com). You can increase the bit-depth of your floating point (to 64-bits, and in some computers, to 128 bits), but that doesn't guarantee you wont have floating-point error or other algorithmic error. You can learn about arbitrary-precision arithmetic; fixed precision calculations, and symbolic algebra systems. But ultimately, if you must prove that a computation has exactly zero error (... because almost exactly zero error isn't good enough! - mathematics is very pedantic!)... then you need to really really really deep dive into the theory of solving equations. Nimur (talk) 03:02, 3 May 2013 (UTC)

It sounds like you'll want to look into using an arbitrary-precision arithmetic library: it'll be much slower than native floating point, but it will avoid rounding issues. You should probably also re-consider your requirements and/or talk to someone with experience in numerical analysis, because having problems with rounding errors is usually a sign you're doing something wrong. --Carnildo (talk) 03:02, 3 May 2013 (UTC)

And, it's very easy to do something wrong without even realizing it. You don't need a complicated algorithm or invalid syntax! Consider the obvious approach to accumulating (adding one) to a floating-point variable:

Naive accumulator algorithm to demonstrate floating point error

#include <stdio.h>
#include <limits.h>
int main() 
{

  float x = 0;
  int i;
  const int max = 100000000;
  for (i = 0; i < max; i++)
     x += 1;
  
  printf("x=%f   max=%d \n", x, max);
  
  return (x == max);
}

The naive approach works on my computer - as long as max is less than something like 16.7 million! And the problem isn't with the syntax; that is perfectly legal C code instructing a computer to increment a value by one a lot of times. Hm... what's special about 16.7 million... might it be almost exactly equal to 2²⁴, where 24 is the bit-length of the mantissa of an IEEE 794 32-bit float? Take a look at the Kahan summation algorithm for the most straightforward error-reduction algorithm for floating-point accumulators. The original post was a request for a sort of polynomial solver - which is a lot more mathematical operations than an increment! It's just a direct computation, but it will suffer from the same numerical problems that a root-finder suffers. You'll want to read and learn all about those, and some of the numerous methods for solving those equations. If you study numerical methods, you'll independently discover that these methods don't work on all your favorite polynomials (... if you have no favorites, your professor will find some new ones for you). Nimur (talk) 03:26, 3 May 2013 (UTC)

In [10] Kahan spends twenty pages on various problems with the usual formula for the roots of a quadratic equation and various ways of fixing them so you don't lose too much precision. This type problem is the impetus for Interval arithmetic so one could get some sort of error bound easily.. Dmcq (talk) 11:32, 3 May 2013 (UTC)

Each of your terms evaluates as something of the order of 1e+13 to 1e+14. With standard (32 bit) floating point arithmetic you get roughly 16 digits of accurracy. If you take the difference between two numbers of order 1e14, you therefore have to expect error of the size 1e-2. That is exactly what you are getting. If the correct result of your calculation is also of the order of 1e+13 (as it will be for most similar choices of a, b, c, d) the error of 1e-2 is acceptable. Just when the result is close to 0, you have a problem. So: either use more than 32bit floats (quadruple precision, arbitrary precision), or rearrange your equation, so that you don't take differences of such large numbers. Not easy in your case, but for example evaluating as a(18bcd-4c^3-27ad^2) - 4b^3d+b^2c^2 on octave returns 0, whereas your original formula gave 0.00390625. Note that this rearrangement still takes differences of number of order 1e+13 (rather than 1e+14), so its success is probably due to luck. Generally you will have a very hard time to reduce the calculation error below 1e-2 when terms of the order 1e+14 are involved. 86.136.42.169 (talk) 23:07, 3 May 2013 (UTC)

Rearranging it as 18abcd + b²c² - (4b³d + 4ac³ + 27a²d²) and using double precision works for me. However, if some of a, b, c, and d are the right negative numbers, you will probably still have the problem. (This sounds like a homework problem for a numerical analysis course.) Bubba73 ^{You talkin' to me?} 05:31, 5 May 2013 (UTC)

The requirement to get exact results when the numbers put in are approximate is a bit odd, after all is it really true the number 10.648 is an exact measurement in decimal? If that is really the requirement then the easiest way is to use an arbitrary precision decimal math package. Otherwise one really needs to figure out exactly how precise the results need to be. One can't in general depend on results being better than single precision after doing a lot of double precision maths and it can turn out worse. Here you need to have 20 decimal digits or more to hold the intermediates if anything straightforward is done and as said above normal double precision only holds about 16 digits and then in binary. Dmcq (talk) 13:18, 5 May 2013 (UTC)

May 3

Syncing files between home and work Win 7 computers including files on network via VPN

I have a laptop and desktop PC at home and my work station at work runs Windows 7. I can access network drives via my work station and via my home laptop and desktop PCs when connected via VPN. Is there some way I can keep copies of files in sync between these systems? I'm not allowed to install anything on the work machine but perhaps there is software that will work via the VPN to update files as needed? --129.215.47.59 (talk) 09:23, 3 May 2013 (UTC)

I’d use a script combined with rsync. ¦ Reisio (talk) 11:55, 3 May 2013 (UTC)

I'd be more comfortable using something with a GUI so I can tell it's working. --129.215.4.176 (talk) 17:10, 3 May 2013 (UTC)

So you can’t, you mean? :p
Check rsync#Solutions_using_rsync and/or list of backup software. ¦ Reisio (talk) 23:28, 3 May 2013 (UTC)

Windows installation not finding new SSD

Hi, I recently bought a SSD and am trying to install a new copy of windows 7 on it. I am finding that the BIOS is recognising it correctly as it appears in the list of booting priorities. However when booting from the windows CD and trying to install it, it isn't finding the drive as a potential place to install. I have tried to switch around SATA cables/power cables, also trying with the original drive and without, with no luck. Booting to the original drive works fine. Is it just that I need to boot to the original drive and install some firmware? Or is there anything else that I need to do? Thanks! (Specs for info: Samsung 840 SSD, WD Seagate barracuda 1.5 Tb, Intel core i7 920, X58 chipset DFI lanparty Motherboard, ATI 4850, usual bits and bobs) Thanks! 80.254.147.164 (talk) 10:48, 3 May 2013 (UTC)

You might find some useful information in http://www.tomshardware.com/forum/294328-32-unable-boot-windows-samsung, particularly the item near the bottom that begins "I found the solution...". (Or maybe not.) Looie496 (talk) 15:11, 3 May 2013 (UTC)

make optical disk look as normal drive

They were this page that work with the depracated ata driver, but how to do this with the new scsi driver or with usb optical reader.

The main purpose is for use with non udf(iso) file system.

Using packet writing is also accepted.I want a sequential access to the block device and not an UDF FS.2A02:8422:1191:6E00:56E6:FCFF:FEDB:2BBA (talk) 12:59, 3 May 2013 (UTC)

To be clear, your goal here is to install an iso file system on some kind of optical disk, in Linux? If so, could you say what kind of optical disk, and what Linux distribution you are using? Looie496 (talk) 15:20, 3 May 2013 (UTC)

I am currently using (enhanced)systemrescuecd but I could accept any other unix even windows/OS2 (it would be the cd-rom handle rather than block device in this case).

By using block device i can do things like put any filesystem (ex:squashfs) on top of the media.

I could accept any media (exept blu-ray and DVD-RAM) but I would prefer CD-RW >700M or CD-R if it doesn't exist.2A02:8422:1191:6E00:56E6:FCFF:FEDB:2BBA (talk) 16:27, 3 May 2013 (UTC)

May 4

Signature pictures containing colored symmetric geometric shapes

In many internet fora, instead of cartoon pictures or a photograph to accompany their username, many users upload images which contain only geometric shapes (several polygons). The images are square, symmetric about the origin (a 90 degrees rotation will yield the same image), and two-colored (the ones I've seen use one color against a white background). For an example, see the bottom of this page, where many of the users use such pictures. My question is simply, what are these called, and what information do they convey. We probably have an article, about this, but I didn't find it. My google-fu a bit weak today maybe, if someone could suggest a search based on the above that would lead straight to the article, that would be instructive too. Thanks, --NorwegianBlue ^talk 08:17, 4 May 2013 (UTC)

Identicon. -- Finlay McWalterჷTalk 10:09, 4 May 2013 (UTC)

In the one system I've seen them used, they're assigned by the site admins, not uploaded by the users. Rojomoke (talk) 10:50, 4 May 2013 (UTC)

Thanks both! It's quite possible that they're assigned by admins, the number of users with identicons in the user-feedback page of Qiqqa is conspicuously high, given that the majority of users would be academics in other fields than computer science. There are two discrepancies between the image that illustrates our article, and the ones in the page I linked to, as well as the ones shown here.

• The image in the article shows mirror-symmetry about both diagonals, whereas the ones I've seen show a four-fold rotational symmetry as described above.
• The image in our article has a lightness gradient in the geometric shapes, the ones I've seen have a single color against a white background.

Does the color in an identicon have a special significance, and is there a symmetry constraint? --NorwegianBlue ^talk 11:10, 4 May 2013 (UTC)

It's a "visual hash" - it takes some data which kinda-sorta-uniquely identifies the user (e.g the IP address) and builds a picture of that. If the particular hash used in this specific site follows Don Park's original code, it takes a 32 bit value (which is the size of an IPv4 address) and computes visual elements based on different bit fields from that 32 bit value - see the comment in Don's code here. I haven't followed through the entire package to see if that's all it does (if there isn't some pre-mangling phase first); if it's that simple, then you should see that similar IP addresses will resolve to very similar Identicons: so if a user moved from 65.32.19.20 to 65.32.19.21, their Identicons should be pretty similar. But other schemes use some confusion and diffusion process (like MD5) to mess the data up before it gets passed to the identicon renderer - that way even a small change in the input data will yield a massive change in the identicon. How a site builds that data will vary; Stack Overflow's scheme (which uses md5, feeding data into the Gravatar identicon engine) is described in this posting. -- Finlay McWalterჷTalk 17:26, 4 May 2013 (UTC)

Thanks a lot! --NorwegianBlue ^talk 05:46, 5 May 2013 (UTC)

Resolved

Partioning

What is the object of partitioning the hard drive on my MacBook Pro and how would I do it please?85.211.128.100 (talk) 12:07, 4 May 2013 (UTC)

Other than just general specialization for various reasons, most likely as part of the installation of an OS. How you’d do it would probably best depend on why it is you want to do it. ¦ Reisio (talk) 12:21, 4 May 2013 (UTC)

The primary reason for having separate partitions (and thus file-systems) is that is easier to reinstall MacOS onto the main partition, should you need to. The installer can recreate the MacOS partition from scratch, and your data is safe on the second partition. It can also make recovery from incorrect shutdowns easier. However, the main disadvantage is that you have to decide in advance how much disk space you want to reserve for applications themselves, and how much for your data from those applications. CS Miller (talk) 14:25, 4 May 2013 (UTC)

Thanks for your thoughts 85.211.128.100 (talk) 05:47, 5 May 2013 (UTC)

Switching users on Twitter

I use several Twitter accounts - one personal, one for work, one for a client. When using it through my browser on my PC it seems I have to log off one account and log on to another in order to tweet or browse from the different accounts. On my iPhone through the Twitter app I can log on as multiple users at once and simply switch from one to the other with two taps to tweet or browse as the different users, without logging off and on. Am I missing something and there's some way to do this on the PC? If not, does anyone know why Twitter build this functionality into their app but not the browser version? (BTW I'm not particularly interested in hearing about third party sites that can do this - I know they can - just wondering about Twitter itself.) --60.230.34.7 (talk) 15:02, 4 May 2013 (UTC)

This functionality is built in to Twitter's own client, TweetDeck (which can be a local client or a single-sign-on web client). Where the browser is the client (without TweetDeck-web), it's the browser that's responsible for managing user identities, and so most of the work is done by the browser's password manager. But you're right, that leaves you with the bother of having to log out of one account and then log into another. That's necessary (usually) because of the way the web works - a web app like Twitter's identifies who is currently logged in (on a given browser) using HTTP cookies. Browsers share the same cookie jar between all their tabs - so if you're logged in as Kevin in one Firefox tab, you're Kevin in all the others too - and logging out in one invalidates the cookie, effectively logging you out on all the other tabs too. That's not Twitter's fault, and there's not much they can do about that; I imagine they'd say "simultaneously managing multiple Twitter accounts is a more advanced activity, and more advanced users should be using TweetDeck rather than the simple webapp". To have multiple concurrent Twitter sessions open in the same browser (or to quickly switch between them, without logging out and in) it's necessary to change the way the browser works - to support that partitioning that, as I said above, it doesn't normally do. Firefox users can do this with the MultiFox extension. -- Finlay McWalterჷTalk 16:48, 4 May 2013 (UTC)

Thanks very much Finlay. That's a very informative response. One workaround I had used a few times was opening multiple browsers, say Firefox and Chrome, and logging in as a different user in each. This explains why that would work if it's basically a matter of cookies associated with the browser. FWIW I've now set myself up on TweetDeck (I had heard of it, but didn't realise that it was actually run by Twitter, or that simultaneously operating as multiple users was one of its features). Looks good. Think I might also take a look at MultiFox. Thanks again. --121.221.235.242 (talk) The user formerly known as 60.230.34.7 02:41, 5 May 2013 (UTC).

Oh, one other question that comes to mind, if anyone knows. Twitter is obviously happy for users to run multiple accounts, however when you go to create a new account it requires you to use a unique email address, i.e., you cannot create an account using an address you've got attached to an existing account. Now if it used the email address as your login name (as many sites do these days) this may make sense, as two users couldn't use the same login-name, but since you log in using your unique username not your email it seems immaterial that the same email address may be attached to more than one account. If Twitter theoretically prohibited multiple accounts it may also make sense, but clearly it doesn't prohibit this. So does anyone know what's up with that? I guess another way of looking at this would be to say why doesn't Twitter allow you to create multiple 'users' under one account, rather like how you can create Pages on Facebook for your organisation, and then post as either yourself or your organisation. ----121.221.235.242 (talk) The user formerly known as 60.230.34.7 06:06, 5 May 2013 (UTC)

Like button on banknote

Are there banknotes on which an URL to the website of the issuing bank or any other reference to an internet resource is displayed? If so, what banknotes?

I'm interested only if the reference is put right on the banknote when it's manufactured, such as printed on it together with other labels and graphics, not for cases when someone stamps an advertisment on banknotes later. Whether the note is currently in circulation doesn't matter.

– b_jonas 17:13, 4 May 2013 (UTC)

The Royal Dutch Mint produced a limited edition 5€ collectible code with a URL to its website encoded on it with a QR code 2d-code.co.uk/qr-code-coin. The Swedish Mint commissioned a new note, the designer of which took it upon himself to put a QR code on it- but the mint didn't like the idea and says that the final notes won't have the code - 2d-code.co.uk/qr-code-banknotes. (urls mangled as the spam filter has an entry for that site)-- Finlay McWalterჷTalk 17:34, 4 May 2013 (UTC)

Thank you for the quick reply. – b_jonas 20:22, 4 May 2013 (UTC)

Turning client-server model into processes sharing memory boosts performance?

There are paragraphs in the book "C++ - Pthread Primer - Multithread Programming":

“ you may be asking yourself this question: “What can threads do that can’t be done by processes sharing memory?”

The first answer is “nothing.” Anything that you can do with threads, you can also do with processes sharing memory. Indeed, a number of vendors implement a significant portion of their threads library in roughly this fashion.

”

And as we know, many applications follow the client-server model, such as XWindow, D-Bus, Metacity window manager, Wayland's compositor, ... etc. I suppose client-server model literally results in slow responses of the applications. As this article mentions XWindow:

“

1. There is a round-trip delay time between client and server (latency rather than from the protocol itself) when a synchronized request is issued.
2. A context switch is required to move between executing client code and server code, if they are running on the same machine.
3. The client and server have to buffer and format commands and responses as per the X Window protocol.
4. On processors with virtually addressed cache, such as ARM 9, context switching between an application and the X server results in a cache flush, further degrading performance.

”

If the applications following client-server model can be rewritten or refactored such that they become processes sharing memory when executing, does it improve responses? (After the rewriting/refactoring, the relationship between the client and the server is more like a "procedure call" rather than an inter-process "communication". So everything fulfills immediately just like calling a procedure, to which I suppose there is no context switch at all and the response should be swift. No?) --- Justin545 (talk) 19:16, 4 May 2013 (UTC)

Don't mistake shared memory, a means of inter-process communication, for what MicroXwin does; the latter is essentially moving the X server into the kernel. "Client server" describes the relationship between two components, not the means of those components communication - a client process and server process can communicate by unix-domain sockets, TCP/IP (network) sockets, shared memory, or other IPC mechanisms like doors. Shared memory IPC is not very much like a procedure call - there are still two processes with two separate instruction pointers and calls stacks, which have nothing to do with shared memory. Because the two processes are asynchronous, there must be a synchronisation mechanism to coordinate use of the shared memory. On unix(alike) systems this is often done with a pthreads semaphore in the shared space. The major advantage of shared memory is not timing, it's that it reduces the amount of copying needed to move data across (other low- or no-copy means of IPC are available). But you still have two processes, there's still latency between the two, and a context switch is still required. -- Finlay McWalterჷTalk 19:33, 4 May 2013 (UTC)

Ok, shm is kind of IPC by definition.

I think context switch is needed only when two or more clients are contending for a shared resource supplied by the server. The later client has to wait until the resource is released by the client that has acquired the resource. So a context switch is needed (it's my mistake). And I think MicroXwin can't get out of this situation even if moving the X server into the kernel. Context switch is still needed or resource can't be released. Except for contended case, I can't figure out any context switch is needed for non-contended case so far. The solution of processes sharing memory and the MicroXwin kernel solution both need to context switch.

And the sentence should be corrected "So everything fulfills immediately just like calling a procedure, to which I suppose there is no context switch at all for non-contended case and the response should be swift in such case.". Still wrong? -- Justin545 (talk) 20:37, 4 May 2013 (UTC)

Incidentally, I see you wrote the MicroXwin article. When is the article going to get independent, reliable sources? It's been tagged as lacking those for four years, and without them it's just an unsourced advert, which I am inclined to nominate for deletion. -- Finlay McWalterჷTalk 19:43, 4 May 2013 (UTC)

Although advertising was not my intention, non-primary sources for it are hard to find. So it's your right to nominate for deletion. -- Justin545 (talk) 20:53, 4 May 2013 (UTC)

In any event, it's worth questioning whether IPC latency is a problem worth bothering about, when considering ordinary user-interfaces of the kind one codes in the X Window System. It's a central matter for games, but games use OpenGL or Direct3D which are architected quite differently. Cambridge University's Computing Laboratory has a nice IPC benchmark suite for Linux, which gives us some comparisons of the raw performance of various IPC mechanisms on various processors. Consider the results for the decade old Opteron 248; even its slowest performer (a local TCP socket, which has to traverse at least part of the TCP stack, two copies, and two task switches) shows latency of 35 µs - that's about 30,000 calls per second. For mempipe_lat (which, if my cursory read of the code is correct, is a test of raw shared memory performance without synchronisation) they get about 1 µs latency - so 100,000 calls per second. Those are orders of magnitude more than a reasonable X gui application needs - and that's on an ancient processor. -- Finlay McWalterჷTalk 20:31, 4 May 2013 (UTC)

Yep, the IPCs may not be the bottleneck as the benchmark demonstrates. But I think context switch and the scheduling algorithm is the real deal in responsible for slow application response, not the IPCs. Because there could be hundreds of processes in the system need to be run in turn by the scheduler, unless there is a mechanism like direct process switch (where during an IPC execution an (incomplete) context switch is performed from the sender directly to the receiver) we are not often able to tell there'll be no other processes take precedence to run between the sender process and the receiver process, which adds extra latency. And synchronized request makes it worse since a round trip is needed to pass the data. That's why I think the client-server design could be improved by the idea of processes sharing memory. -- Justin545 (talk) 22:55, 4 May 2013 (UTC)

May 5

Copying a CD via iTunes

Probably a silly question, but something that's puzzled me for a while. When copying tracks from a CD to a computer hard drive using iTunes (and presumably with other similar software) I often notice that the first few tracks copy slowly, but the rate of copying speeds up as the CD nears the end. The first few tracks may copy at 12x playing speed, say, but by the last track it'sll be copying at around 20x. Presumably there's some technical reason for this... but what? Thanks in advance, Grutness...wha? 03:52, 5 May 2013 (UTC)

I don't know, but perhaps the fact that CDs write from the inside out, and the outside of the disc spins faster? Is there any references for this theory? Mingmingla (talk) 04:00, 5 May 2013 (UTC)

I have no source, but yes, it's because the data is written in a spiral starting from the inner edge at a constant linear density, and the bottleneck is not the decoding but the angular speed of the disc, which has to be limited to avoid noise, vibration, and shattered CDs. -- BenRG 04:15, 5 May 2013 (UTC)

What is The use of Thread class constructors?

Hi!My doubt is on Thread class constructors
1)public Thread()
2)public Thread(String name)
The above two are two constructors of thread class.
First constructor is used to create object of thread class.
Second constructor is also used to create object of thread class with required name.
If we write
1)Thread t1=new Thread();
This creates a thread class object t1.
2)Thread t2=newThread(“MYTHREAD”);
This also creates Thread class object t2 .It also creates thread with name "MYTHREAD".
My questions are
1)What is the benefit of above t1,t2;
2)How can we use the thread class objects t1,t2?
3)Is it possible to execute run method of the thread "MYMTHREAD"?
4)Suppose we have extended class named “a” from Thread class like below.
Then how can we use t1,t2 on below class “a”?
Is it possible to create thread to below class “a” with required name by using above constructors?

Class  a  extends Thread  
{  
Public void run()  
{  
System.out.println(“Hi”);  
}  
}

--Me shankara (talk) 05:16, 5 May 2013 (UTC)shankara

Threads have names only for debugging purposes (urgh, maybe serialization too, but doing that is a bit naff). You can't (natively) getThreadByName. A thread implementation could chose to mark the native thread with the name (if the OS supported that), so thread names showed up as something more informative than "java" when viewed with native debug and trace tools(e.g. top, pstree, ps); although that mechanism exists on Linux (via prctl), it looks like the OpenJDK thread implementation at least doesn't use it (I've not tried other OSes or other Java runtimes). So with that, all you can do with a thread name is print it, when you have a handle to the Thread object. This is still pretty handy - run the program below and you'll see that the thread name helps clarify which threads are "ours" and which are utility things that the runtime itself created:

import java.util.Map;

public class SleepyThreads implements Runnable {
    public static void snooze(int ms){
    	try {
            Thread.sleep(ms);
        }
	catch (InterruptedException e) {}
    }

    static final int THREAD_COUNT=5;
    static volatile boolean keep_running=true;

    public static final void main(String [] args) {
        Thread [] slaves = new Thread[THREAD_COUNT];
        for(int i=0; i< THREAD_COUNT; i++){
            slaves[i] = new Thread(new SleepyThreads(), "SleepyThread("+Integer.toString(i)+")");
            slaves[i].start();
        }

	snooze(5*1000);

        Map<Thread,StackTraceElement[]> m = Thread.getAllStackTraces();

        keep_running=false; // makes all the slaves quit                                                            
        snooze(100); // wait a bit, so the slaves dying prints don't mess up with later prints                      

        for (Map.Entry<Thread,StackTraceElement[]> entry: m.entrySet()){
            System.out.println("\n---" + entry.getKey());
            for(StackTraceElement e: entry.getValue()) {
                System.out.println("   " + e);
            }
        }
    }

    public void run() {
        while(SleepyThreads.keep_running){
            System.out.println("name:" + Thread.currentThread().getName());
            snooze((int)Math.random()*500);
        }
    }
}

-- Finlay McWalterჷTalk 11:57, 5 May 2013 (UTC)

WINDOWS 7 - HIDDEN FUNCTIONS

Are there any more hidden functions in windows 7 other than sticky notes, sound recorder and snipping tool? thank you.175.157.233.231 (talk) 12:41, 5 May 2013 (UTC)