Wikipedia:Reference desk/Archives/Computing/2009 September 5

= September 5 =

E-mail
Why do students with a school e-mail address often create another address for the purpose of joining sites like Youtube, Myspace, Facebook, Gamefaqs, etc? Jc iindyysgvxc (talk) 00:37, 5 September 2009 (UTC)


 * There are lots of possible reasons, if the above is actually true.
 * School addresses necessarily expire. Unless you are a graduate student, of course, in which case you can have the same one for a decade. Yay!
 * School addresses are seen as rather "official," being explicitly joined to a real, physical identity. Not everybody wants these places like Youtube, Facebook, etc., to have access to their real-world identity. They might want a little more anonymity.
 * School addresses may have specific terms of service that make them undesirable for wider use.
 * School addresses may require POP3/IMAP enabled mail readers to access them, where webmail is sometimes more convenient. Similarly, one might want to diversify one's incoming e-mail—to keep the school things on the school address, and everything else on the webmail address. This is advantageous also in terms of spam.
 * Lastly, there is no worse place in the world for reliable IT services than a school. Academics always underfund their IT departments drastically, and this leads to all sorts of mayhem on a regular basis. Every university I've attended has had major IT problems—stolen data, overheated servers, ridiculously small inbox quotas, you name it. If you want reliable e-mail, your local university is probably the last place you'd want to go.
 * The above is just speculation. I'm not sure there is a definite trend, nor am I sure the causality is right here. (In my experience, students often already have gmail addresses when they arrive at school, and then have the school mail just forward to that, for what they are used to.) It also probably differs depending what level of "school" you are talking about (high school? undergraduate at college? graduate school?). Again, this might not even be true—is there any evidence that this is a major trend? --98.217.14.211 (talk) 00:50, 5 September 2009 (UTC)


 * The above statements are generally true, although some schools offer lifetime email addresses to alumni. One other reason may be that the student used their yahoo/hotmail/gmail before entering college and that is their primary email. -- Guroadrunner (talk) 16:58, 5 September 2009 (UTC)
 * Though the "lifetime" e-mail addresses are often different anyway (e.g. @alumni.uni.edu vs. @uni.edu) --98.217.14.211 (talk) 18:46, 5 September 2009 (UTC)
 * Another issue is the naming conventions. While someplaces are relaxed and let you choose your address, others have rigid naming rules and will *force* you to have the email address of WILBERFORCE_TIBERUS_VIJAYARAGHAVENSATYANARYANAMURTHY (at) schoolname.edu, when everyone knows you as "Billy V". Get a Gmail/Hotmail address, and you're the much more user-friendly billyv_23 (at) gmail.com
 * But the reason I use a separate address is the spam issue. The address I give out to websites, mailing lists, etc. gets hundreeds of spam messages a day, whereas the address I only give out to friends, family and "official" contacts gets a couple dozen per week at most. -- 128.104.112.179 (talk) 17:48, 5 September 2009 (UTC)


 * Actually, worse than the long names are that most require you to have short names. There is nothing so emasculating as having your proud, long last name (John Q. Izzardly, III) truncated into some sort of horrible Unix username (jizzard@uni.edu). --98.217.14.211 (talk) 18:45, 5 September 2009 (UTC)
 * Probably the most simple reason is the fact that sites such as myspace and Facebook arent accessable through school, we were blocked from all these sites which resulted in the emails being of no use inside college and school email was very slow to access outside of college.195.49.180.146 (talk) 12:57, 7 September 2009 (UTC)


 * Increasingly, you ARE your email address. Ideally, you'd want to keep the same address your entire life.  I've used steve at sjbaker dot org for close to 15 years now.  The mail server it's directed towards has been linked, redirected, forwarded and moved around more times than you can count - but it's the "one true place" where people can always get hold of me.  People who I have not talked to in 10 years can (and do) still find me there.  Knowing my email address also lets them guess my web-site URL - which is another huge win.  Changing your email address frequently is a really terrible idea from a communications standpoint...although the brief spam-holiday you get is often welcome!  So if (for some reason) you're required to use a school address (for example, because teachers are ignoring mail from other addresses) - then it makes sense to redirect it to your 'permanent' address for the duration of your time in school - knowing full well that when you graduate, you'll have a new address - but your 'permanent' one can always redirect to it. SteveBaker (talk) 16:33, 7 September 2009 (UTC)

Importing bookmarks from Firefox into Opera
Can somebody tell me where to find my Firefox bookmarks? I am trying to import them to Opera and, unlike Chrome, it makes me look for them rather than just doing it automatically (actually, I never managed it with Chrome - it just went on for ages before I gave up - both times). --KageTora - (영호 (影虎)) (talk) 02:26, 5 September 2009 (UTC)


 * I think Transmute will fit your needs nicely. It transferred my Chrome bookmarks to Firefox almost by itself.-- The Ninth Bright Shiner 03:12, 5 September 2009 (UTC)


 * Thanks. I downloaded that, but it's not quite what I wanted. Anyway, for reference, I found out how to do it here on the Mozilla website. --KageTora - (영호 (影虎)) (talk) 12:00, 5 September 2009 (UTC)

Excel 2007 being absolutely dense
Sometimes it baffles me how freeware can outdo a bazillion-dollar office suite.

Let's take this hypothetical situation here:

Column 1 | Column 2 | Column 3 Row A  106    |          |    99 Row B         |    90    |

Very simple, no? I want to start a line graph and add on to it as new values arise. However, the fact that there's a gap between the 106 and 99 is just far too troublesome for Excel, so it doesn't connect the values. I'm left with three standalone points when I really should have one standalone and two connected.

OpenOffice.org Calc, hilariously, does not do this. Meaning you can have oodles of columns between one value and the next, and two values will still connect. Now while I love Calc, I'm trying to transition back to Office ever since I re-obtained it. I'd rather have the correct graph on Excel if possible. Is there any way to make Excel connect those points?

And yes, I realize I could put "102.5" in Row A, Column 2, but I feel like I would be winning the battle only to lose the war, know what I mean?

The problem is that you have introduced 3 'y' co-ordinates and provided only 2 values. The problem is with using a Line Chart. If Excel draws a line directly from 106-99 then anybody reading that chart will think that the value for Column 2 must be something between 106-99. Because Excel does not have a value in the field it assumes it is a missing data point so does not connect the data to it. It could assume the null-value is equal to 0 (in which case yourl line-chart would go from 106-0-99 and look like a 'v') but that wouldn't be a very good assumption as it's rare that someone has a 3 point chart, but pieces of missing data in 100-data-point Y axis is easily handled and looks sensible (the data shows a line, it breaks, then resumes - showing a data-point missing an entry.

I would suggest that OpenOffice is incorrect because it fails to note that there is no entry in column 2 for Row A and by connecting the dots leaves the reader (anybody other than the creator) to assume that Column 2's row A value must be something between 106 and 99. ny156uk (talk) 09:32, 5 September 2009 (UTC)
 * Well I won't say which is right or wrong - surely there should be an option to turn this on or off - perhaps there is - if so, what/where is it?83.100.250.79 (talk) 11:42, 5 September 2009 (UTC)


 * If there is an option in Excel, I've never found it, despite LOTS of looking. It is incredibly irritating. I've resorted numerous times to making two data sets -- one where the missing points are averaged, and one which they are not, and then making the one where they are not have data markers so you can see where the actual data is. The truth is Excel is an awful, idiotic program, and is not capable of making good-looking, useful graphs at all (it is, however, great at making misleading, 3-D, colorful graphs, which are apparently what people use in the business world today, despite their inability to convey information). --98.217.14.211 (talk) 14:35, 5 September 2009 (UTC)
 * I often wondered what it is like to have a job where I can just create a few pi and bar charts and talk about "market trends" - ah, to live in bullshit castle, what a dream!83.100.250.79 (talk) 19:49, 5 September 2009 (UTC)
 * My biggest complaint is that Excel (and other visual data analysis tools) readily apply trendlines and spline fits to data which should not have either. Unfortunately, it has trained a generation of "data analysts" that you can just "put" a curvey line through any data points, whenever you want, without thinking (and assume the result is meaningful).  Interpolation will soon be a lost art... Nimur (talk) 18:26, 5 September 2009 (UTC)


 * The problem with Excel, at its heart, is that it does not give serious people the ability to really manipulate how the data is displayed, and encourages people to take a rather non-serious attitude towards visualization of data (hey, maybe this is an X,Y chart? or maybe it is a bar chart? how about a web! let's make it in 3-D, while we're at it!). It is, like the rest of Microsoft Office, geared towards middle-management. Alas, the rest of us have to use it too (or open-source programs that faithfully replicate all of its flaws). --98.217.14.211 (talk) 01:51, 6 September 2009 (UTC)

Importing sound files to Scratch
What kind of file types does scratch (MIT) accept when I import sound files?--Mikespedia (talk) 05:09, 5 September 2009 (UTC)

Windows Problems
On every Windows XP or Vista computer I've ever used - my own, public computers, etc - after leaving the computer on for more than a day or so it starts to act up, goes extremely slow and makes hard drive rumbling sounds even when all programs are closed and the computer is supposedly idol. More mysterious, in task manager there are no processes making read / writes, yet the hard drive rumbles away like it's been formatted or something. Why is this? Why does restarting the computer fix this problem for the next 24 hours, then it comes back? —Preceding unsigned comment added by 82.43.88.99 (talk) 10:04, 5 September 2009 (UTC)


 * This sounds like the proverbial "When did you stop beating your wife?" question. I'm sure there will be a few Mac and Linux folks that will have a ball answering this, but - I'll give it a meager shot. (Although I've run both XP and Vista for over a month without a need to reboot).  Anyway ... think of your memory (RAM) like a chalkboard.  You keep writing, then using a dry eraser to to remove things when your done.  Eventually, all the "dust" still on the chalkboard needs to be completely "washed off". (reboot).  There are memory managers that can help with this, but essentially the computer is looking for a clean spot to write stuff.  Hope that helps a little. — Ched :  ?  10:17, 5 September 2009 (UTC)
 * I don't understand what you're trying to imply with that loaded question. Anyway, thank you for the answer. I'm not really sure what ram has to do with hard drive rumbling though, could this be the swab file?
 * There is no "dust" that needs to be "washed off". Some things that might cause disk activity during idle time are background defragmentation, shrinking the page file, and background indexing. The first two of those probably wouldn't show up as reads/writes in Task Manager. They can all be disabled and they shouldn't slow down your work because they stop when the machine stops being idle. NT does have an annoying habit of discarding perfectly good pages from RAM when the machine has been idle for long enough, which causes a temporary slowdown and disk activity when you start using it again. Other than that I don't know what your problem could be. -- BenRG (talk) 11:14, 5 September 2009 (UTC)
 * It sounds vaguely like an antivirus program constantly scanning the hard disk - which locks up the hard disk - but doesn't use that much resources - since the hard disk is the bottleneck - could this be it.83.100.250.79 (talk) 11:37, 5 September 2009 (UTC)


 * I don't know about your systems, but I have had Windows XP computers with persistent uptimes longer than 500 days. (The only need for a reboot, if I recall, was after upgrading to XP SP2).  My current Windows XP system is reporting an uptime of over 7 days at the moment.  I think Windows, like any operating system, can be stable or unstable, depending on the installed software; good luck with hardware and drivers; and generally, making sure the system setup is well-thought-out.  The operator's or administrator's capabilities are a major contributing factor, but sometimes you just get some bad luck with a wacky audio-card or disk controller that occasionally freezes up the machine.  As far as the "gradual decay" towards sluggishness, I have not seen this behavior on Windows XP, though I remember it was always a problem on older systems (Windows 95 in particular).  As I mentioned, one of my WinXP systems ran for most of two years without a reboot, and I never saw a performance slowdown.  I suspect you have some buggy software running on your machine; it's probably not the operating system's fault.  Nimur (talk) 18:07, 5 September 2009 (UTC)
 * Just to correct Ched, RAM is constantly being written to and read from, it is not like a chalkboard -- if you look at it like that, it is being wiped off constantly. I find that after about 20 days of uptime my computer slows down noticeably. I don't understand how you are reading HDD read/writes from taskmgr, because it doesn't show them (as far as I know, but I don't run Vista, and it would surprise me if Microsoft implemented that in such a core feature). — neuro  (talk)  18:47, 5 September 2009 (UTC)
 * You can add I/O information to the XP Task Manager's process view in View → Select Columns. -- BenRG (talk) 19:02, 5 September 2009 (UTC)
 * I only see that option on the view menu on the networking tab. — neuro  (talk)  19:09, 5 September 2009 (UTC)


 * On Windows 98, RAM was often not freed up by programs after using it. In Windows XP this was noticeably improved to the point of not being a problem. --98.217.14.211 (talk) 03:55, 6 September 2009 (UTC)


 * In the past, (pre-WinXP) it was undoubtedly true that you needed to reboot your Windows machines at least daily. Microsoft even told you to do that!  Linux and Mac users could rightly point to up-times measured in years without slowdowns or crashes.  But I have to grudginly accept that Windows has gradually gotten better - the WinXP machine I use at work goes for weeks to maybe a month before needing a reboot.  The reason for needing to do so at all is usually a slow leakage of resources due to almost insignificant bugs that slowly, but inexorably, cripple the system.  A lot also depends on the kinds of use you put your computer to - and on how sensitive you are to performance.  I'm a game programmer - I measure where every millisecond goes - and every millisecond is precious - so I'm spectacularly sensitive to problems like this!.   Some programs and usage-patterns impose more of a stress than others - some may 'tickle' particular bugs - it's really tough to say why (in detail) this happens on a general basis.  When it gets bad - reboot - and while it's rebooting, think about how much nicer it would be to be using Linux. SteveBaker (talk) 16:17, 7 September 2009 (UTC)
 * Windows didn't gradually improve, it improved suddenly with the switch from Win9x to NT. Any slow leakage of resources on your machine is not NT's fault. If your 3D graphics programming is bluescreening your computer, that's ATI or Nvidia's fault. -- BenRG (talk) 20:08, 7 September 2009 (UTC)

Linux cp of home directories

 * 1) What are the correct options to give to cp to recursively copy a directory, maintaining file ownerships+groups, file permissions, including .hidden files, and let softlinks remain softlinks? I'm copying the /home subtree to a different disk. I have read the manpage, but the number of options is quite large, and the explanations terse. In case there are distro-variations, I'm using Ubuntu and Debian, and the file systems are ext3.
 * 2) Is there any reason not to replace the /home subtree with a softlink to a subdirectory on a different disk?
 * Thanks, --NorwegianBluetalk 13:04, 5 September 2009 (UTC)
 * "cp -a /home /new/home" as root should do it. As for the second question, theoretically some program might get confused by /home being a softlink, but that would certainly be a bug.  84.239.160.214 (talk) 13:26, 5 September 2009 (UTC)
 * Thanks! --NorwegianBluetalk 13:52, 5 September 2009 (UTC)


 * I've always used 'tar' for this:

cd fromdir ; tar cf -. | ( cd todir ; tar xf - )


 * It preserves links, sym-links, ownerships and privilages, etc - so long as the person doing the copying has the relevant permissions. There are a bunch more command line arguments to fine-tune what gets duplicated and what doesn't. SteveBaker (talk) 16:05, 7 September 2009 (UTC)
 * Thanks. Presumably the -a option achieves the same thing (the 'a' is short for archive), but as you say there are a bunch of command line arguments. The directories in question are small enough for me to use both approaches and compare. --NorwegianBluetalk 19:06, 8 September 2009 (UTC)

three way merge sort
i have done 2 way merge sort ..

but now i want 2 do it by three way ...

please give sort function and merge function in detail in c-programme language..

hope i will get it earlier as there is mine exam soon.. —Preceding unsigned comment added by Yogeshlahane (talk • contribs) 19:04, 5 September 2009 (UTC)


 * Wikipedia does not do your homework for you. Please read the header. — neuro  (talk)  19:06, 5 September 2009 (UTC)


 * We have a mergesort article, which shows the 2-fold way of doing it. I've never heard of someone doing it 3-fold (and I doubt it'd be more efficient), but the 3-fold implementation is an obvious extension of 2-fold - where you split into two, split instead into three. When merging, your merge function needs to be able to compare values from the three sublists. -- Finlay McWalter • Talk 19:52, 5 September 2009 (UTC)


 * If you are going to try a 3-way merge sort, you would just be baby-stepping into parallel sorting algorithms. Performing it on one processor doesn't provide a benefit.  Doing an n-way merge sort on n processors will have a benefit (limited heavily by Amdahl's law.  Of course, there are many other parallel sorting algorithms that are far superior to parallel merge sort. --  k a i n a w &trade; 20:50, 5 September 2009 (UTC)
 * Was I wrong to read this as a homework question? I still read it that way, just curious if I am misreading. — neuro  (talk)  22:35, 5 September 2009 (UTC)


 * It may very well be a homework question. Good. There is no proscription against answering homework questions; we just don't do the homework for the guy. If, as it seems, the OP needs a C implementation of 3-way mergesort, and doesn't want to do the work himself, he was SOL before he asked, and he's SOL now. If he wants to do the work himself, but was just somewhat confused, then we've helped in an appropriate and educational way. -- Finlay McWalter • Talk 22:53, 5 September 2009 (UTC)


 * If the algorithm is done by hand an n-way merge is more effective. Imagine sorting a big stack of paper.  I often do this myself when sorting books, splitting into 5 or 6 stacks is good.  This is where the effort of moving is much bigger then the effort of identifying the next one to pick. Just keep picking the smallest off each stack that is bigger than than the last one you picked, until you can't do it any more, then pick the smallest again to start a new run. Graeme Bartlett (talk) 22:35, 5 September 2009 (UTC)
 * In the olden days of computing where there were no disk drives, but card sorters and tape drives, the most effective would be to read as many tapes at the same time for a merge, as you could. The idea is to reduce the number of operator tape mounts. Graeme Bartlett (talk) 22:57, 6 September 2009 (UTC)

Tracing travel route on map
I am trying to create graphics of our travel route (for a family photo album). Can anyone suggest a program / website I could use for this? I would like to trace our route as lines across a map. I tried Google Maps, but it puts massive markers at every stop which I would like to avoid if possible... &mdash; QuantumEleven 21:26, 5 September 2009 (UTC)
 * Bing Maps. Hit "Collections" -> "Open your collections". At the bottom of the collections box is a row of six or seven icons. Next to the pushpin tool is a path tool. It will measure distance as well and you can hit "print" to print the path and the surrounding map. Xenon54 / talk / 21:34, 5 September 2009 (UTC)
 * I believe Google Earth will do that as well, but it has 3D buildings and some other cool stuff. Thanks,  gENIUS 101  01:15, 6 September 2009 (UTC)
 * You can draw lines on Google Maps instead of dropping pointers (and have those lines follow roads automatically). -- k a i n a w &trade; 21:04, 7 September 2009 (UTC)

home networking, what equipment do i need?
the situation is that i'm moving into a large house with lots of other people, there is an existing ethernet network, ie internet comes into the house and each person gets an ethernet port in there room. Now i have several bits of equipment that use the internet and would like to make a "mini-home network" ie i have one device to plug everything into (as i only have one port in the room). Now i would like to be able to set up a network so i can share files between my computers easily and securely and preferably it would need wireless, though i could live without it

the problem i have is what do i actually look for? routers seem to need to be connected to the internet access (ADSL or cable), bridges just seem like a way to expanding the range of stuff, i think i need a switch but none of them ever seem to have wireless, is a switch what i should be looking for? and if so does anyone where i can get one with wireless ability?--90.221.74.56 (talk) 21:49, 5 September 2009 (UTC)


 * You need a router. The name router has been misused to commonly refer to router/modem combos which is what you've described. If you want to have a network that's pretty much inaccessible from the main LAN then you need a router, one with a WAN port and a/some LAN ports and wireless capability. If you just want to extend the main network and make all your equipment to be part of the main network then you need an ethernet switch, and a wireless access point for wireless. --antilivedT 01:59, 6 September 2009 (UTC)

Writing Guidelines

 * I've moved this question to New contributors' help page, as that seems like the appropriate venue for this subject. -- Finlay McWalter • Talk 23:39, 5 September 2009 (UTC)

Searching in Google - what is "clients1.google.co.uk"?
After every key is pressed in a search, it will have a message in the firefox toolbar "waiting for clients1.google.co.uk". Is this keystroke logging?--Nothingwrongwithit (talk) 23:45, 5 September 2009 (UTC)


 * It's Google Suggest sending what you've typed so far to Google to provide you with that dropdown list of suggestions. You can turn it off here (bottom of the page) if you don't want the suggestions. — Matt Eason (Talk &#149; Contribs) 23:59, 5 September 2009 (UTC)


 * (ec) This notes that it's a server associated with Google Suggest. That latter link tells you how to turn it off. -- Finlay McWalter • Talk 00:01, 6 September 2009 (UTC)