=== InHisName1 is now known as HowdyDoody [05:14] I am trying to modify a desktop icon to also add an environment variable before executing the program to call. It seems to ignore the env settting. Do I have some bad syntax here ? -->Exec=/usr/bin/env PYTHONPATH=/usr/lib/virtualbox/:/usr/lib/virtualbox/sdk/bindings/xpcom/python/ gksudo python "/opt/GNS3/gns3" [10:30] Morning [13:08] Morning peoples [18:50] waltman: hey. Are you around? I need some math help [18:50] CS/math help [18:54] 2 [18:54] jedijf: 3 [18:55] damn; i was guessing 1+1 [18:55] heh [19:02] waltman: really though... [19:17] MutantTurkey: yo [19:20] MutantTurkey: log_2(n) [19:21] but why? [19:21] it's always log_2(n) [19:22] ok, sometimes it's 2^n [19:22] waltman: so I got a job rewriting matlab into C... one of our programs uses the NNLS algorithm (it's built into matlab), but I am having trouble finding a C counterpart... [19:23] and our file sizes are a bit ridiculous [19:23] but really I am having trouble understadning the function [19:23] waltman: I comprehend how least squares works, at least in theory, but I don't understand the non-negative aspect of non-negative least squares [19:24] ok, let me take a look at it. [19:25] http://amath.colorado.edu/computing/Matlab/OldTechDocs/ref/nnls.html [19:25] what can I show you? [19:26] wait they're using the lsqnonneg function actually. [19:26] matlab obsoleted it and it's not in 2012a (which is the version I have) [19:28] I have 2012a, yeah it's lsqnonneg now [19:28] waltman: btw drexel has 2012b up as well if you wanted it [19:28] I need to stick with the version we run at work. [19:29] gotcha [19:29] I didn't realize there were many versioning issues [19:29] matlab noob here [19:30] best to just stick with the same version [19:30] gotcha [19:30] MutantTurkey: Well, you could try to dig up a copy of that book or some other books on least squares... [19:31] I found a book in temples library, maybe I'll go grab it tomorrow [19:33] here's an entire phd thesis on the problem: https://smartech.gatech.edu/bitstream/handle/1853/31768/?sequence=1 [19:34] only 35 citations? wtf? [19:34] well fk a whole damned thesis... [19:35] waltman: what a sucker... only 35 citations... [19:35] I got as far as pseudocode for the algorithm, and it didn't look like something I'd want to write if I didn't have to [19:35] You are now either in over your head or loverloaded with useful information. [19:35] ChinnoDog: far over [19:36] MutantTurkey: Anyway, as you've no doubt figured out by now, I've never heard of this version of the algorithm. [19:37] crud [19:37] MutantTurkey: It seems perfectly reasonable to ask your professor if he knows of any code that might do this. [19:37] shr' [19:37] she' [19:37] but yes, we found some implementations that are really slow [19:38] aka didn't work [19:38] because the matrix size is like 160 millio [19:39] maybe there's an implementation for octave? If so, you could at least see how it's implemented. [19:39] do you mean 160mil x 160mil? [19:40] no 160mil by 1 i think [19:40] 160mil by 100 i mean [19:40] a lot of data, not a lot of other stuff [19:41] in that lsnonneg function there are two arguments, what is that second argument containing? I don't really get it [19:41] waltman: it's actually 160milx1024 [19:45] my guess is that you're trying to minimize the solution of Cx = d [19:45] but again, I think you'd be much better off discussing this with your prof [19:45] I concur [19:45] bbiab [19:45] but I sound like an idiot [19:46] "durr whats a vector durr" [19:46] No one expects college freshmen to understand linear algebra [19:46] laundry & [19:49] ok thanks :) [19:52] waltman: i have a few more idiot questions... [19:58] I should also point out that if you're back at Drexel, Ko's students know a lot more about least squares than I do. [19:58] (which is not very much) [19:59] really you think? [19:59] they always impress me [19:59] but I am also a burden unto them :p [19:59] I don't know much about least squares. They use it a fair bit. [19:59] waltman: so I how do I load data into matlab? [19:59] :p [19:59] that I do know! [20:00] the format is sparse, like this: [20:00] SPARSE [20:00] row height [20:00] total rows [20:00] 1 1 .242462 (row col value) [20:00] for the rest [20:00] http://www.mathworks.com/help/matlab/ref/spconvert.html [20:00] does matlab understand that? [20:00] thanks [20:01] thats exactly it! [20:01] BTW That was the first hit on google for "load sparse matrix into matlab" [20:02] lol yeah [20:02] I am trying that as well [20:03] waltman: if it is reading this Gb sized file in, can i tell matlab to load another file in at the same time? [20:06] You could try, but it seems unlikely. You've only got the single command window, right? How are you could to do it? [20:07] matlab seems mainly single threaded to me. asking it to do two things at the same time, even if you could, seems like a bad idea. [20:09] yeah [20:09] ugh, my English got mangled there. [20:10] It seems to me that when you're in the command window, you've got to wait for one command to finish before you can run another one. [20:10] right [20:12] waltman: ugh matlab prints out the whole matrix once loaded... [20:12] oh god [20:12] oh god [20:13] MutantTurkey: That's because you forgot to end the statement with a ; [20:13] you might try Ctrc-C [20:13] Ctrl-C [20:16] woul that interpt it though? [20:16] the command? [20:16] No, I'm pretty sure it has to finish, because it's showing you the answer. [20:16] ok gotcha