| === InHisName1 is now known as HowdyDoody | ||
| HowdyDoody | 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" | 05:14 |
|---|---|---|
| rmg51 | Morning | 10:30 |
| teddy-dbear | Morning peoples | 13:08 |
| MutantTurkey | waltman: hey. Are you around? I need some math help | 18:50 |
| MutantTurkey | CS/math help | 18:50 |
| jedijf | 2 | 18:54 |
| MutantTurkey | jedijf: 3 | 18:54 |
| jedijf | damn; i was guessing 1+1 | 18:55 |
| MutantTurkey | heh | 18:55 |
| MutantTurkey | waltman: really though... | 19:02 |
| waltman | MutantTurkey: yo | 19:17 |
| waltman | MutantTurkey: log_2(n) | 19:20 |
| MutantTurkey | but why? | 19:21 |
| waltman | it's always log_2(n) | 19:21 |
| waltman | ok, sometimes it's 2^n | 19:22 |
| MutantTurkey | 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... | 19:22 |
| MutantTurkey | and our file sizes are a bit ridiculous | 19:23 |
| MutantTurkey | but really I am having trouble understadning the function | 19:23 |
| MutantTurkey | 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 | 19:23 |
| waltman | ok, let me take a look at it. | 19:24 |
| MutantTurkey | http://amath.colorado.edu/computing/Matlab/OldTechDocs/ref/nnls.html | 19:25 |
| MutantTurkey | what can I show you? | 19:25 |
| MutantTurkey | wait they're using the lsqnonneg function actually. | 19:26 |
| waltman | matlab obsoleted it and it's not in 2012a (which is the version I have) | 19:26 |
| MutantTurkey | I have 2012a, yeah it's lsqnonneg now | 19:28 |
| MutantTurkey | waltman: btw drexel has 2012b up as well if you wanted it | 19:28 |
| waltman | I need to stick with the version we run at work. | 19:28 |
| MutantTurkey | gotcha | 19:29 |
| MutantTurkey | I didn't realize there were many versioning issues | 19:29 |
| MutantTurkey | matlab noob here | 19:29 |
| waltman | best to just stick with the same version | 19:30 |
| MutantTurkey | gotcha | 19:30 |
| waltman | MutantTurkey: Well, you could try to dig up a copy of that book or some other books on least squares... | 19:30 |
| MutantTurkey | I found a book in temples library, maybe I'll go grab it tomorrow | 19:31 |
| waltman | here's an entire phd thesis on the problem: https://smartech.gatech.edu/bitstream/handle/1853/31768/?sequence=1 | 19:33 |
| waltman | only 35 citations? wtf? | 19:34 |
| MutantTurkey | well fk a whole damned thesis... | 19:34 |
| MutantTurkey | waltman: what a sucker... only 35 citations... | 19:35 |
| waltman | 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 |
| ChinnoDog | You are now either in over your head or loverloaded with useful information. | 19:35 |
| MutantTurkey | ChinnoDog: far over | 19:35 |
| waltman | MutantTurkey: Anyway, as you've no doubt figured out by now, I've never heard of this version of the algorithm. | 19:36 |
| MutantTurkey | crud | 19:37 |
| waltman | MutantTurkey: It seems perfectly reasonable to ask your professor if he knows of any code that might do this. | 19:37 |
| MutantTurkey | shr' | 19:37 |
| MutantTurkey | she' | 19:37 |
| MutantTurkey | but yes, we found some implementations that are really slow | 19:37 |
| MutantTurkey | aka didn't work | 19:38 |
| MutantTurkey | because the matrix size is like 160 millio | 19:38 |
| waltman | maybe there's an implementation for octave? If so, you could at least see how it's implemented. | 19:39 |
| waltman | do you mean 160mil x 160mil? | 19:39 |
| MutantTurkey | no 160mil by 1 i think | 19:40 |
| MutantTurkey | 160mil by 100 i mean | 19:40 |
| MutantTurkey | a lot of data, not a lot of other stuff | 19:40 |
| MutantTurkey | in that lsnonneg function there are two arguments, what is that second argument containing? I don't really get it | 19:41 |
| MutantTurkey | waltman: it's actually 160milx1024 | 19:41 |
| waltman | my guess is that you're trying to minimize the solution of Cx = d | 19:45 |
| waltman | but again, I think you'd be much better off discussing this with your prof | 19:45 |
| MutantTurkey | I concur | 19:45 |
| waltman | bbiab | 19:45 |
| MutantTurkey | but I sound like an idiot | 19:45 |
| MutantTurkey | "durr whats a vector durr" | 19:46 |
| waltman | No one expects college freshmen to understand linear algebra | 19:46 |
| waltman | laundry & | 19:46 |
| MutantTurkey | ok thanks :) | 19:49 |
| MutantTurkey | waltman: i have a few more idiot questions... | 19:52 |
| waltman | 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 |
| waltman | (which is not very much) | 19:58 |
| MutantTurkey | really you think? | 19:59 |
| MutantTurkey | they always impress me | 19:59 |
| MutantTurkey | but I am also a burden unto them :p | 19:59 |
| waltman | I don't know much about least squares. They use it a fair bit. | 19:59 |
| MutantTurkey | waltman: so I how do I load data into matlab? | 19:59 |
| MutantTurkey | :p | 19:59 |
| waltman | that I do know! | 19:59 |
| MutantTurkey | the format is sparse, like this: | 20:00 |
| MutantTurkey | SPARSE | 20:00 |
| MutantTurkey | row height | 20:00 |
| MutantTurkey | total rows | 20:00 |
| MutantTurkey | 1 1 .242462 (row col value) | 20:00 |
| MutantTurkey | for the rest | 20:00 |
| waltman | http://www.mathworks.com/help/matlab/ref/spconvert.html | 20:00 |
| MutantTurkey | does matlab understand that? | 20:00 |
| MutantTurkey | thanks | 20:00 |
| MutantTurkey | thats exactly it! | 20:01 |
| waltman | BTW That was the first hit on google for "load sparse matrix into matlab" | 20:01 |
| MutantTurkey | lol yeah | 20:02 |
| MutantTurkey | I am trying that as well | 20:02 |
| MutantTurkey | waltman: if it is reading this Gb sized file in, can i tell matlab to load another file in at the same time? | 20:03 |
| waltman | You could try, but it seems unlikely. You've only got the single command window, right? How are you could to do it? | 20:06 |
| waltman | 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. | 20:07 |
| MutantTurkey | yeah | 20:09 |
| waltman | ugh, my English got mangled there. | 20:09 |
| waltman | 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 |
| MutantTurkey | right | 20:10 |
| MutantTurkey | waltman: ugh matlab prints out the whole matrix once loaded... | 20:12 |
| MutantTurkey | oh god | 20:12 |
| MutantTurkey | oh god | 20:12 |
| waltman | MutantTurkey: That's because you forgot to end the statement with a ; | 20:13 |
| waltman | you might try Ctrc-C | 20:13 |
| waltman | Ctrl-C | 20:13 |
| MutantTurkey | woul that interpt it though? | 20:16 |
| MutantTurkey | the command? | 20:16 |
| waltman | No, I'm pretty sure it has to finish, because it's showing you the answer. | 20:16 |
| MutantTurkey | ok gotcha | 20:16 |
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