| --- Log opened Mon May 02 00:00:10 2011 |
| --- Day changed Mon May 02 2011 |
| 00:00 | < simon_> | sorry... so long as B' != M |
| 00:03 | < simon_> | ah... I can do something with coprimes. |
| 00:03 | < simon_> | (I just needed to do some loud thinking here) |
| 00:10 | < Rikushadow5> | Refresh my memory |
| 00:10 | < Rikushadow5> | What does != mean again? |
| 00:11 | < McMartin> | "Is not equal to" |
| 00:11 | < Rikushadow5> | ah |
| 00:11 | < Rikushadow5> | I usually use =/= for that. |
| 00:11 | < Rikushadow5> | GOSH, C, WAY TO BE CONFUSING. |
| 00:13 | < Finerty> | That is the standard symbol for inequality testing in modern programming languages |
| 00:14 | < simon_> | != and <> are most commonly used. |
| 00:15 | < Finerty> | Though I haven't seen <> outside of Excel in like 20 years. |
| 00:19 | < simon_> | ML uses it |
| 00:20 | < simon_> | also Pascal |
| 00:21 | < simon_> | Rikushadow5, are you a mathematician? |
| 00:21 | < Rikushadow5> | Not really |
| 00:21 | < Rikushadow5> | I'm kinda good with numbers, but I don't know all of those fancy things they teach people in college |
| 00:24 | < simon_> | I can't decide if I should be studying math or psychology. I'm kind of afraid of studying math. :) |
| 00:31 | < simon_> | at Copenhagen University, some feminist students of medicine made this collection of pictures of vaginas for educational purposes. |
| 00:32 | < simon_> | they made this website where you can click refresh and see new pictures. it's supposed to replace the archaic drawings in educational material and better teach young women of the diversity of genitalia. |
| 00:33 | < simon_> | they have only got about 100+ pictures, and they show nine at a time, so often the same picture will show up twice, and often a picture will just switch places when refresh is hit. so now I'm sending them a number generator that will produce a random stream of numbers that will exhaust their picture collection before making a new random order. |
| 00:34 | < simon_> | it's mostly a joke I made when I was drunk, but now I'm doing it and writing them a letter pretending to have been sitting and staring at pictures of vaginas for hours before detecting a pattern, but offering a piece of code that will fix this for future viewing pleasure. |
| 00:35 | < simon_> | someone suggested that I should make a javascript browser plugin to fix this "bug" until they update their website. as if the resource is widely used and regularly updated. heh. |
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| 01:25 | < gnolam> | simon_: *snerk* |
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| 01:28 | | * Finerty examines simon's question. |
| 01:28 | < Finerty> | Simon: you want to choose N /distinct/ random numbers from 0..M? |
| 01:29 | < Finerty> | Your best bet for deterministic-time results is a standard shuffle algorithm. |
| 01:29 | < gnolam> | E.g. Fisher-Yates. |
| 01:31 | < Finerty> | The method described on wikipedia works, but usually I rejigger it so the shuffled stuff is at the start. |
| 01:32 | < Finerty> | In either case, you'll need O(N) time and O(M) (or, with an approrpriate sparse-array implementation, O(N)) space. |
| 01:34 | < simon_> | thanks, both of you. I'll go with a shuffle. |
| 01:34 | < Finerty> | (but using a sparse array impl will blow up your k, and isn't worth it unless M is unfathomably large.) |
| 01:35 | < simon_> | also, I have all numbers from 0..M exactly once, so I would be able to obtain little sparsity. |
| 01:36 | | McMartin [mcmartin@1526F6.B1ED4D.379C75.6B300E] has quit [[NS] Quit: kernel upgrade] |
| 01:36 | < ToxicFrog> | Am I confused, or did we have this same conversation a few days ago and settle on Fisher-Yates Shuffle that time, too? |
| 01:37 | < Finerty> | A quick grep says "not here" |
| 01:38 | < simon_> | ToxicFrog, I might've asked this question a year ago. |
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| 06:46 | | * McMartin grumbles about basically undocumented filesystem operations. |
| 06:46 | < McMartin> | Which people aren't supposed to use, but use anyway, and as a result we have to adapt to them. |
| 06:47 | < McMartin> | But! |
| 06:47 | < McMartin> | It looks like we have this one nailed. |
| 06:47 | < McMartin> | So \o/ to that. |
| 06:57 | < Kazriko> | which one? |
| 06:58 | < McMartin> | Crazy problem at work. I've been being vague, just tearing my hair out a little about it. |
| 06:58 | < McMartin> | Two conflicting device drivers, plus the Windows Search Service, plus an antivirus, all interacting at once. |
| 06:58 | < Kazriko> | Ohh, file system operations, not filesystems. heh |
| 06:59 | < McMartin> | Yeah. |
| 06:59 | < McMartin> | (NTFS "oplocks", which are semidocumented things that are used by background system things to make attempts to open them hang until the op is completed, instead of giving a sharing violation error. Lets the desktop search etc do its work without apps noticing.) |
| 07:02 | < Kazriko> | Ah. |
| 07:04 | < McMartin> | (The drivers got in a fight with the AV, resulting in Explorer getting hung up for five minutes at a stretch due to oplock hangs.) |
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| 07:35 | < Kazriko> | McMartin, and those lengthy hangs are part of why I disable that service every time I install windows. Or used to, at least. |
| 07:40 | < McMartin> | The oplock technique wasn't properly done until Win7, IIRC, and as such it's really terrible until that point. |
| 07:52 | < froztbyte> | messyfs |
| 07:53 | < froztbyte> | although ntfs is definitely a few steps up on the vfat family |
| 07:53 | < froztbyte> | and then they went and did that exFAT shite... |
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| 11:00 | < McMartin> | Is there actually a way to have gcc produce out-of-band debugging symbols? |
| 11:01 | < McMartin> | .pdbs make a lot of distribution issues easier since you can distribute a stripped binary and then reinstate debugging info after the fact. It seems like the "more primitive" way to do it, but I don't know of any gcc options for actually doing it that way. |
| 11:02 | < jerith> | I'm not sure. I very seldom compile anything these days. |
| 11:02 | < McMartin> | (PDB being the MS version of this) |
| 11:02 | < jerith> | To me, "pdb" is a tool for debugging Python code. |
| 11:02 | < McMartin> | Yes, it's that in Windows too; hilarity ensues. |
| 11:03 | < McMartin> | This one is "Program Data Base", not "Python De-Bugger". |
| 11:04 | < McMartin> | But the fact that we can back-form full stack traces with symbols from stripped release builds is one reason we haven't switched the Win32 version of UQM over to MinGW yet, and it'd be nice if there were a way to have a single build flow. |
| 11:06 | < jerith> | McMartin: http://stackoverflow.com/questions/866721/how-to-generate-gcc-debug-symbol-outsi de-the-build-target |
| 11:06 | < jerith> | Is that useful? |
| 11:08 | < jerith> | Looks like you build with debug symbols, then use "strip" to separate them out. |
| 11:08 | < TheWatcher> | I'm not aware of any argument to gcc that will do what you want, jerith's link describes the only way I've run into to do it. |
| 11:13 | < TheWatcher> | http://sourceware.org/gdb/current/onlinedocs/gdb/Separate-Debug-Files.html#Separ ate-Debug-Files descives the use of objcopy/strip so I assume this is their 'expected' method for it |
| 11:13 | < TheWatcher> | *describes |
| 11:14 | < McMartin> | Nod |
| 11:14 | < McMartin> | Easy enough to script, at any rate. |
| 11:15 | < McMartin> | Yes, this is in fact exactly what I'm looking for. |
| 11:16 | < TheWatcher> | buggered if I know why gcc doesn't have and argument to do it, though. It's not like it doesn't have 20 million already >.> |
| 11:16 | < McMartin> | And I should probably consider doing that for the Mac build as-is. |
| 11:16 | < McMartin> | Yeah, this is why I figured I'd just missed one~ |
| 11:16 | < McMartin> | Cheers again |
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| 17:14 | | * gnolam flails vaguely at disk management. |
| 17:14 | < gnolam> | Apparently, formatting a 2 TB drive takes a while. :P |
| 17:27 | < Tarinaky> | Gee, ya think?# |
| 17:27 | < Tarinaky> | :p |
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| 17:56 | < simon_> | depends on the FS, no? :) |
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| 19:16 | | * Vornucopia perpares an integer sequence for possible inclusion in OEIS |
| 19:18 | < celticminstrel> | Ooh. |
| 19:19 | < Vornucopia> | (specifically: the largest prime needed to perform trial division on each number n.) |
| 19:28 | < simon_> | trial division? |
| 19:30 | < ToxicFrog> | OEIS? |
| 19:30 | < Vornucopia> | Online Encyclopedia of Integer Sequences. |
| 19:31 | < Vornucopia> | Trial Division: to prime factorize a number, try dividing it by 2, then by 3, then 5, etc, until you have found them all. |
| 19:32 | < Vornucopia> | for instance, starting with 522: 522/2 = 261, 261/2 = 130r1, 261/3 = 87, 87/3 = 29, 29/3 = 9r2, 29/5 = 5r4, and then we're done, so 522 = 2 * 3^2 * 29 |
| 19:37 | < Phox> | Why? Math's always fascinated by prime numbers, but what does prime factorization do? |
| 19:38 | < Vornucopia> | Prime factorization, well. Okay, so: every whole number can be factored into a list of prime numbers (well, technically a multiset) in exactly one way. |
| 19:39 | < Vornucopia> | You can use a number's prime factorization for many things; most common (in teaching math at least) is using them to reduce fractions and to find a common denominator with which to add or subtract fractions. |
| 19:39 | < Vornucopia> | Prime numbers also have a number of other convenient features which causes them to show up a lot in, for instance, cryptography and random number generation. |
| 19:42 | < Vornucopia> | If you can prime factorize someone's public key in certain kinds of cryptography, you have his private key; this however is a spectaularly difficult thing for numbers of the size currently used. |
| 19:48 | | * Vornucopia fiddles, determines that excel really, really doesn't like being forced to do this. :) |
| 19:50 | < simon_> | factorization or fiddling? |
| 19:51 | < Vornucopia> | Factorization. |
| 19:53 | | * Vornucopia gives up, grabs other sequences from oeis to get the right answer. |
| 19:59 | < Vornucopia> | Would be easier if I had a real programming language I could use on here. |
| 20:03 | < Vornucopia> | Well, whichever. That's 100 terms of the sequence, I think that will do. |
| 20:06 | < simon_> | I don't know, it seems like it could be useful. |
| 20:07 | < simon_> | in spite of the upper bound sqrt(n). |
| 20:09 | < Vornucopia> | It's actually max(second highest prime factor, highest prime below sqrt(highest prime factor) |
| 20:09 | < Vornucopia> | ) |
| 20:13 | < Vornucopia> | So when I get home and have my actual code tools available I can generate as many of these as I feel like. |
| 20:19 | | SmithKurosaki [smith@4FC299.382CB9.EF1529.A5B039] has joined #code |
| 20:47 | < Vornucopia> | (I think it'd be interesting to see how the needed number changes over time.) |
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| 21:21 | < ToxicFrog> | Vornucopia: you can't use a real programming language where you are? |
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| 21:24 | < Vornucopia> | TF: not really. Well I mean I could do C I guess, but that and list-building number theory is probably a Bad Idea. |
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| 21:28 | < ToxicFrog> | Blargh. |
| 21:28 | < ToxicFrog> | Can't even remote into anything? |
| 21:29 | < Vornucopia> | This is the second time in three minutes that I have said "I need to set up a server at home" |
| 21:34 | < RichardBarrell> | Or rent one. |
| 21:34 | < ToxicFrog> | Setting one up at home is easier and cheaper, if you have spare hardware to run it on. |
| 21:35 | < RichardBarrell> | You could use EC2 or something in that family. |
| 21:35 | < RichardBarrell> | They have atrocious value for money, but really low minimum costs. |
| 21:35 | < Vornucopia> | I have spare hardware. |
| 21:36 | < Vornucopia> | More hard drives than your body has room for. |
| 21:44 | | * ToxicFrog begins work on the tentatively named EmuFun |
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| 21:45 | < Vornucopia> | emuf... what? |
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| 21:45 | < 459AADCOO> | Obviously, it must be an emu petting farm |
| 21:45 | < 459AADCOO> | Why else would he call it that? |
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| 21:47 | | * Vornucopia must go anyway. Will check in later. |
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| --- Log closed Tue May 03 00:00:45 2011 |