Computing desk
< October 29	<< Sep \| October \| Nov >>	October 31 >

Welcome to the Wikipedia Computing Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

October 30

Khan Academy web exercise subjects besides math

At Khan Academy, in the Vision section describing the major components, it says: Automated exercises with continuous assessment (already over 70 modules mainly in math). I've done all the ones I could see in my dashboard (84) and I can say that all the exercises I saw were in math. I could supply a list to prove this, but it would make this post very long. So was whoever wrote those words "mainly in math" not using the most accurate language, or are there automated exercises in other categories that I'm not seeing? Thanks. 76.27.175.80 (talk) 00:33, 30 October 2010 (UTC)[reply]

As you admit, there may be automated exercises in other categories that you're not seeing. The section in the article seems to be referenced by a youtube video posted by the academy (although I've not checked whether the reference does in fact check out; let us assume it does). In general, we prefer article content based on reliable sources which can be verified. If you can find a reliable source backing your assertion, then please amend the article. thanks --Tagishsimon (talk) 00:43, 30 October 2010 (UTC)[reply]

Clustered Computing - Booting & Cluster Shared Volumes

Hello Everyone.

In a cluster of computers, do each of the servers have its own boot volume, or do all servers in a cluster boot from the same volume? The Wikipedia article on clustered computing doesn't make this clear. I'm aware that all nodes in cluster store data on on the same cluster shared volume, so my question is only about where each node's operating-system is stored.

Thank you to all respondents. Rocketshiporion♫ 03:22, 30 October 2010 (UTC)[reply]

It doesn't have to be one way or another. I have set up Beowulf clusters to use independent boot volumes per computer. I've also set them up to use network booting from a single master server. -- kainaw ™ 01:14, 31 October 2010 (UTC)[reply]

I should clarify my question. Do all nodes in a cluster boot from a single LUN, sharing a single system image, or does each node have its own system image on its own LUN? Rocketshiporion♫ 02:46, 1 November 2010 (UTC)[reply]

That is the question that I answered. I have set up Beowulf clusters such that each node (computer) was completely independent. It shared no drives with any other computer. It was completely separated except for the network cable used for inter-node communications. I have also set up clusters such that the nodes (computers) all booted from a single master server image. -- kainaw ™ 13:01, 1 November 2010 (UTC)[reply]

Static functions in C

Hello Sir/Madam,

I have a small doubt in c, Especially using function. That is prototype declaration of function and function declaration. static function(int *,float *);//prototype here using static declaration is

static function(int *a,float *b)
{
  my Coding....
}

and the other one is function(int *,float *);//prototype no storage class

declaration is

function(int *a,float *b)
{
  my Coding....
}

what is the difference between the above two function. (one is normal function another one is using the storage class.) why do we use static storage class while declaring function and what is the purpose?

Thanks . M.Antony prabhu —Preceding unsigned comment added by 122.164.59.55 (talk) 03:42, 30 October 2010 (UTC)[reply]

Added header and formatted spacing -- kainaw ™ 03:56, 30 October 2010 (UTC)[reply]

The keyword "static" means a lot of things in C. With functions, it refers to the scope of the function. Without static, you can use "extern" to use a function from one source file in another source file. If you make the function static, you cannot use extern on it. So, "static" has limited the scope of the function. I looked for a very short/simple example and found this. -- kainaw ™ 04:03, 30 October 2010 (UTC)[reply]

"You recently visited the following sites"

1) This http://www.privacy-test.info/ reveals that websites can see what other websites I visited in the past. Is there any way in Firefox to avoid revealing this information without having to clear or disable History, which I like to keep?

2) The drop down menu of the box that shows the URLs in Firefox shows a random selection of webpages that I visited months ago (and different from the above). How does Firefox decide which websites to show?

3) Is there any way to edit the information in 1) or 2) above?

4) Apart from using a proxy, what can I do to reveal as little about myself and my computer as possible when surfing? Thanks 92.15.12.85 (talk) 15:44, 30 October 2010 (UTC)[reply]

Firefox in private browsing mode and using noscript 'http://noscript.net/' is a good start at keeping a low profile. SemanticMantis (talk) 16:16, 30 October 2010 (UTC)[reply]

I thought that private browsing mode merely prevented any record being left on your computer, and not information being released to the internet? 92.15.12.85 (talk) 17:54, 30 October 2010 (UTC)[reply]

You can use an encrypted VPN or TOR to hide your IP, and CCleaner to remove cookies (browser, flash, but not all of java).Smallman12q (talk) 16:43, 30 October 2010 (UTC)[reply]

I believe the suggestionss at [1] will do it although it's not something I've tested or looked in to in depth myself. Nil Einne (talk) 01:16, 31 October 2010 (UTC)[reply]

For question 2: Firefox's algorithm for choosing websites in the URL bar dropdown is called the "Awesome Bar" (no, seriously). See here. Searching for "awesomebar options" or the like should give you some information on configuring it, but there aren't very many easily-editable checkboxes and the like. « Aaron Rotenberg « Talk « 03:25, 31 October 2010 (UTC)[reply]

I find it shocking that you are required to give any personal information at all, or have these mis-named "cookies" infesting one's computer - "Rats" would be a better name. It's like going into a shop and being required to give your full name, address, dob, previous addreses, employer, marital status, blood group, fingerprint, etc etc.; or being required to give the full spec and history of your car plus where you've been in the last couple of days when in a petrol filling station. Who's bright idea was it to request all this info? 92.15.26.46 (talk) 15:27, 31 October 2010 (UTC)[reply]

Not a Frequent Flyer then ? Sfan00 IMG (talk) 16:55, 31 October 2010 (UTC)[reply]

Wireless router requiring reboot

I fully expect this question to be far too vague as to be answerable, but just on the off-chance that someone here knows someone that tech support doesn't, I've come here again. I have a relatively new dsl modem/wireless router that I have registered my laptop and iPhone on, and after a few hiccups during installation it basically works fine, except for the fact that I need to perform some combination of modem reboot (the wireless and modem are combined in a single unit) and wireless ethernet card off/on (via the external switch on my laptop) to get it to work, every time my computer reboots. If I don't reinitiate both every single time the computer boots up (hibernating it has the same effect) I either get stuck in "unidentified network" or it just doesn't work limiting me to "local network only". Tech support brilliantly informs me to reboot the modem and turn off my machine, which of course, fixes the problem, but I'm wondering why the heck I have to do this every single time my computer starts up. I'm using Vista home, my internet service is Telus (Vancouver, Canada) and I live in an apartment, if any of that is important.

Does this situation sound familiar to anyone? Thanks! 173.183.73.136 (talk) 18:34, 30 October 2010 (UTC)[reply]

I can't answer your question, except that the situation sounds familiar because I have similar problems on my (Vista) laptop. My problem seems to occur most regularly after I've been connected to a different network. Often just manually disconnecting and reconnecting (from the network and Sharing Center) seems to resolve the problem. Dbfirs 09:26, 31 October 2010 (UTC)[reply]

Did you check your ISP settings? Generally, when you buy internet service, they provide you with a username and password to use the service. My wireless router at home has randomly deleted our ISP login information before, and this sounds very much like the same symptoms when my router lost the login. The easiest thing to do is to go into the wireless settings (open command prompt and type "ipconfig" Take the IP address, type it into your web browser, and change the last digit grouping to "1.") This should allow you to access the modem preferences. Then re-enter your username and password.

If you don't know your username or password, call your ISP and they will be happy to tell you. If you don't understand what I'm saying, feel free to leave a message on My talk and I'll try to explain a different way.Matthewrbowker (talk) 21:15, 31 October 2010 (UTC)[reply]

If the router has lost the ISP settings, then rebooting it wouldn't solve the problem would it? The problem sounds more likely to be the computer forgetting the logon to the router, or the router not listening for the computer's logon, or not transmitting its ID. Dbfirs 23:04, 31 October 2010 (UTC)[reply]

It does actually connect, it just doesn't get a response, so it doesn't seem to be a problem on the computer side (my iPhone also sometimes has trouble connecting, but not every time). I'm wondering what can possibly be done to remind the router to look for my computer, or to force it to send its ID. 173.183.73.136 (talk) 06:41, 4 November 2010 (UTC)[reply]

If you log in to your router's management, you can choose whether or not the router broadcasts its ID. I think it's the computer that searches for the router, not the other way round. The router just listens and should respond. I wonder if there is some Radio Frequency interference nearby. I had trouble with a TV wireless transmitter that seems to work on a similar frequency. You can test this out by trying to connect with a device right next to the router, then at a distance. If interference is the problem, then connection will be much more reliable near to the router. When you say "doesn't get a response", do you mean that no bytes are received from the router? (shown in wireless router status) If this is the case, then no connection has been made. If bytes are received as well as sent, then the connection has been made, and you should be able to see other devices (if permitted) on the network. If you still have no internet after a connection is made (two-way communication), then the problem is likely to be in your router/modem's connection to the internet. I'm not an expert on this, but I have shared the same sort of frustration. Dbfirs 00:27, 5 November 2010 (UTC)[reply]