Wikipedia:Reference desk/Archives/Computing/2009 June 7

= June 7 =

Linux on older laptop: recommendations?
Could anyone recommend a user-friendly Linux installation that would run well on a laptop with 128 mb RAM ("Toshiba Satellite Pro 4600")? I'll just say the laptop is running Windows NT right now, and beyond a slow boot-up, it seems to function OK with NT. Thank you, Outriggr (talk) 00:38, 7 June 2009 (UTC)


 * Damn Small Linux and Puppy Linux; Puppy is really quite nice. Hopper Mine (talk) 00:57, 7 June 2009 (UTC)
 * (ec) Well, I have had good experience with running Xubuntu (Ubuntu with XFCE) on a laptop with 256MB of RAM. Xubuntu is the most "old computer friendly" official Ubuntu flavor, but if you have a look at http://help.ubuntu.com/community/Installation/LowMemorySystems, it explains how to install even less resource using window managers. ~ fl 00:59, 7 June 2009 (UTC)
 * (2ec) I've found Puppy Linux pretty effective on older hardware. It has good hardware detection, a lot of applications squashed into a small distribution and can be run in memory straight from the CD or pen drive.  The current version is 4.2, but if that doesn't work for you try the slightly older 2.17  - both can be downloaded (in the form of .ISO CD images) from the offical site or one of its mirrors.  Astronaut (talk) 01:00, 7 June 2009 (UTC)


 * I think I'll try Xubuntu first as I'm looking for a traditional hard-drive install (where I get to purge a half-decade of corporate non-admin WinNT crappiness in the process :). Tx for all ideas, Outriggr (talk) 01:11, 7 June 2009 (UTC)
 * So it's the usual death of a thousand cuts with Linux (last used, years ago). I downloaded and installed Xubuntu alternate. It's working, but not at native laptop screen resolution, and Xfce has no option to change to higher than 800x600. So I search the internet--oh, maybe I need to change "\etc\x11\xorg.conf" settings (currently a blank file, so I'm thinking that's not going to magically fix it either). But I can't save the change, presumably because my account isn't an admin. So I try to log in as root, after changing the password. But the GUI won't let me log in as root. Whatever... and it's about two thirds slower than WinNT was. Laptop=doorstop I guess. My only goal with this system is to make it a cheap "ebook reader": To transfer PDF files to it with a USB stick (which works) and b) read them from the screen, but I'm not getting the real estate. I'll try one more "lightweight" Linux distro before swearing it off forever. I thought things were supposed to have changed. Outriggr (talk) 08:00, 7 June 2009 (UTC)
 * Well to be fair, I don't know how it was "years ago", but nowadays, no one does (or should) login as root. Pressing Alt+F2 will bring up a Run dialog, and typing gksu mousepad /etc/X11/xorg.conf (notice the capital X, it's important, and would be why the file is "empty" when you try an access it) will open up editing of that file as root. Good luck in your search! ~ fl 08:25, 7 June 2009 (UTC)


 * If you're talking about slowness to repaint windows and the like, it's probably due to the use of a slow fallback video driver and will go away once you fix that problem. -- BenRG (talk) 18:40, 7 June 2009 (UTC)


 * Well I've just tried Xubuntu on two machines, running as a live CD in both cases. On the pretty new laptop, it ran nice and fast, with no problems (true, I couldn't change the screen resolution, but 1280x800 was quite good enough for me).  On the much older desktop machine (~10 years old, 400mhz PII, 640MB, with 17" CRT), the maximum 1280x1024 screen resolution was also good, but it was a lot slower - no big surprise there, but it was noticably slower than Puppy Linux installed in a disk partition on the same machine.  Astronaut (talk) 21:07, 7 June 2009 (UTC)


 * Apologies for my earlier whining (I'd burnt the CD(RW) three times and attempted installation four times by that point. A little frustrated.) Fl, I was able to edit the .conf file, to no effect. I found that the system would regenerate the .conf file as well if it was corrupt (due to my spelling error), which didn't help. I'm guessing the resolution problem is due to a lack of specific-enough video driver (having read "man xorg.conf"). Would I be better to give up and try a different distro, or attempt to install a video driver (without knowing how, at this point). Thanks again, if you're still reading. Outriggr (talk) 23:19, 7 June 2009 (UTC)

Rainbow function
(also might be one for maths and science)

Can anyone suggest a mathematical function for generating a rainbow of colours. (Not a look up table) - I've already made one but I'm not 100% satisfied with it - it has the colours in it - but doesn'r really look 'rainbowy' (ie as in My Little Pony. Along the same lines - the RGB spectra of a reallife rainbow - is anyone aware of a function used to curve fit to it (in terms of the RGB values) since that might be useful. Finally - question 3 - although I said I didn't want one - what about look up tables - are there any well known ones for a good rainbow. ?  —Preceding unsigned comment added by 77.86.10.194 (talk) 00:56, 7 June 2009 (UTC)


 * The secret of all colour work is to think not in RGB space (RGB is for machines), but in HSL space. For a rainbow you want S (saturation) at full, V at 50%, and the n coloured bands you want are H values that equidistantly fill the space (which is a polar coord); so if you wanted 6 colours they'd have Hs of 0,60,120,180,240,and 300 degrees. You need to convert HSL to RGB for output, but most graphics libraries have utility functions to do that. Hopper Mine (talk) 01:11, 7 June 2009 (UTC)


 * Note that using the HSL space like Hopper Mine suggested will not really give you "true rainbow colors" in the sense that it includes magenta (H = 300&deg;), which isn't a spectral color. The solution is, don't use the whole hue space, just divide the arc up to about 280° instead of 360°. &mdash; Kieff | Talk 01:22, 7 June 2009 (UTC)
 * Thanks -good link - so I need HSV-RGB-comparison.svg up to somewher between 240 and 300. I had Rainspec.PNG which was doing a similar thing - except a little skewed... (it's a graph if the intensities - not the rainbow itself..) The HSL_and_HSV is pretty handy too.


 * All the same I was aiming a somthing even more cartoony and stylistically 'rainbowy' - if anyone has any suggestions. —Preceding unsigned comment added by HappyUR (talk • contribs) 01:47, 7 June 2009 (UTC)
 * If you want a cartoony rainbow then just pick some colors that look good to you. Judging by pictures like this, the My Little Pony illustrators don't care much about scientific accuracy. Accurate reproduction of a real rainbow is complicated. This page has some information. -- BenRG (talk) 12:47, 7 June 2009 (UTC)
 * Thanks, another useful link. What would be really useful is a mathematical approximation to those response curves - actually if anyone can supply actual points (data) for the curves I could have a go at that myself. It looks like a cubic might be able to give a fairly close fit. —Preceding unsigned comment added by 77.86.10.194 (talk) 22:02, 7 June 2009 (UTC)
 * You can get the raw data here. You probably don't want the RGB color matching functions given there since they use the wrong RGB color space. Instead download the XYZ color matching functions, then multiply by the matrix given at sRGB#The forward transformation to get sRGB color matching functions. Then force those into the [0,1] range by adding white and scaling and whatever else, then convert them from linear to nonlinear with the formula given later in the section, then multiply by 255 and round to the nearest integer. Most people use the CIE 1931 2° functions, but the Judd–Vos modified functions will probably give you a slightly more accurate rainbow. -- BenRG (talk) 00:09, 8 June 2009 (UTC)
 * Thanks - I tried but was a bit dubious as the images on http://www.techmind.org/colour/spectra.html didn't look anything special, however after finally getting the functions to work (I think? is there supposed to be clipping?) it worked really well - especially in terms of the 'purple fring' at far blue, that I was failing to get right in my guesses. It came out most like image b in the above link but seems better. I was going to upload it but the licensing seems overly tedious since I would have to mention all those references in from the site I got the data off - interesting that there is only a very small patch that is only blue. Consider this resolved and thank you very much.

Intelligence as absence of stupidity
It is often said that "intelligence has its limits, but stupidity knows no bounds." This suggests that intelligence is merely the absence of stupidity, just as cold and darkness are the absence of light and heat (hence there is a minimum possible temperature but no maximum possible temperature), and that as a perfect vacuum would be perfectly dark, so too would it be perfectly intelligent. Is it possible, then, that computers and other inanimate objects could be made more intelligent not by adding anything to them but by extirpating the stupidity from them? Neon Merlin  06:48, 7 June 2009 (UTC)


 * I think your argument could go either way; one could also argue that stupidity is the absence of intelligence, but that's the standard view. Anyway, you might be interested in Panpsychism, the theory that everything in the universe has consciousness and intelligence (to some degree or another). Indeterminate (talk) 07:04, 7 June 2009 (UTC)


 * Actually, stupidity is the absence of intelligence. Intelligence is the ability to understand things, and stupidity is an absence of it. To say that intelligence is a lack of stupidity is to say that intelligence is a lack of a lack of understanding.


 * In order to make programs more intelligent, you generally have to add more code to do more things, and then run them on more powerful CPUs. Note that humans are more intelligent than other animals because our brains are larger and have more neurons. That allows us to ponder more complex thoughts. Likewise, more powerful CPUs allow computers to run (ponder) more complex programs (thoughts).--WinRAR anodeeven (talk) 07:08, 7 June 2009 (UTC)


 * I think intelligence is the added substance; stupidity is the base. There is definitely a lower-bound on stupidity, as defined as a lack of intelligence processing. Inanimate objects are about as stupid as it goes—it makes no sense to think of anything possibly being stupider than them, they has a net intelligence of zero. Once you start adding a brain, intelligence becomes a factor of increased brain size, capacity, wiring, etc. Intelligence is the light; stupidity is the dark. There's no really defensible other position on it if you are thinking in terms of what cognition really means. Stupidity is the absence of intelligence—plain and simple. --98.217.14.211 (talk) 15:13, 7 June 2009 (UTC)


 * "The Wikipedia reference desk works like a library reference desk." Ontology is perhaps somewhere to direct your inquiry, though. 98.169.163.20 (talk) 02:58, 8 June 2009 (UTC)

Epson R2880 Printing Onto Canvas
Dear all, I'm not sure if there's any way out of this other than trying to use a windows machine to install the drivers, but any help would be appreciated.

I am trying to print onto a roll of epson premium canvas satin using a macbook pro OS 10.5, photoshop elements 4.0 and the epson stylus R2880. Nowhere, and I do mean nowhere, is the the option to choose "watercolor paper-radiant white"(as dictated by the documentation with the roll paper) to be found. Not in the printer driver, not in the print options from photoshop, and also the tools icon to change options is also not to be found. I am only able to change the media type to roll paper A3 from the print menu in photoshop, but this does not permit printing as the correct type of paper cannot be selected alongside in order to tell the printer it should be printing onto a roll of canvas.

The epson manual says that OS 10.5 will not show the print tools icon, and that refusing to share the printer could help, but it doesn't.

I have also checked the ink cartridges so that the matte black is installed, and none of the cartridges has been used yet, so ink volume is not a problem.

A friend of mine using windows said he has had no problems, and I fear that using a windows machine could be my oly option. The epson call centre didn't reply in 50mins today so I hung up.

Any offers?

Lukerees1983 (talk) 12:31, 7 June 2009 (UTC)


 * Well, it is Sunday. Your call probably got routed to the 3-person backup team.  But even if you called again tomorrow, they might not be that helpful - in my experience many support teams only offer decent support if you have Windows.
 * As for the "watercolor paper-radiant white" how important is it to have this exact setting. Maybe your Mac driver has a similar setting that will work just as well.  Astronaut (talk) 13:49, 7 June 2009 (UTC)
 * I can understand you don't want to experiment too much, as that canvas sounds expensive. However, regardless of paper quality settings, a printer will just print on whatever you actually feed to it. You do need a roll setting so it won't try to eject after a page. Choose the print quality setting closest to the canvas surface, ie if it is porous use a plain-paper setting, if it doesn't suck moisture when you test it with water, use a gloss-paper setting. If you can spare a single sheet piece, use it to test print small areas on various settings, to see which gives fair resolution without colour bleeding. KoolerStill (talk) 20:06, 7 June 2009 (UTC)

Fuse.conf access denied (Linux security)
I need to access the file /etc/fuse.conf (on Ubuntu), to make a project I am working on work. However, this file is not readable by non-root users, and I am planning to make it world-readable. Do you think that is a security risk? (I need it to be able to mount files with FUSE with the "allow_other" option, so I need to enable "user_allow_other" in fuse.conf) thanks_ Hacktolive (talk) 18:03, 7 June 2009 (UTC)
 * No, you just need to add yourself to the "fuse" group. The /etc/fuse.conf file is readable to to the fuse group. --76.173.203.58 (talk) 02:27, 8 June 2009 (UTC)
 * Thanks. Hacktolive (talk) 11:42, 8 June 2009 (UTC)