| --- Log opened Thu Aug 01 00:00:37 2013 | ||
| -!- munaafghumran [~mg0950@eduroam-wireless-pat4.nomadic.bris.ac.uk] has joined #mageec | 09:11 | |
| munaafghumran | jeremybennett: could you introduce me to Nigel and Albert for the ML discussions please | 09:12 |
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| @jeremybennett | munaafghumran: Thanks for the reminder. I'm just on a call at the moment. If you haven't seen an email by 1:30, please ping me again! | 11:05 |
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| AWhetter | jeremybennett: On the benchmarks, why did you decide to use rand() instead of jrand()? | 11:48 |
| jamespallister | rand is part of the standard library | 11:54 |
| jamespallister | jrand was a hack by me when i couldn't get the std library to work | 11:54 |
| AWhetter | Is rand reproducible though? I'm getting inconsistencies across arm and x86 which makes self-verifying difficult. | 11:57 |
| @simoncook | is it the same rand on all targets/seeded the same? | 12:00 |
| AWhetter | It might be that newlib is doing rand differently on ARM, but it's seeded the same | 12:02 |
| @simoncook | It would surprise me if glibc and newlib rand is exactly the same | 12:03 |
| AWhetter | Can I use jrand then? | 12:08 |
| jamespallister | rand is not random | 12:11 |
| jamespallister | pseudo random, with a seed | 12:11 |
| jamespallister | I thought the C standard library specified the specific formula that rand had to be | 12:11 |
| jamespallister | although I'm not sure on that | 12:14 |
| jamespallister | jeremybennett, amylaar_, any ideas? | 12:14 |
| @jeremybennett | I suggest do a few quick tests. | 12:14 |
| amylaar_ | man pages are often helpful. | 12:15 |
| amylaar_ | For a definite answer with regards to the standard, you have to look at the standard, of course. | 12:16 |
| amylaar_ | I remember that I've submitted some *rand* patches for newlib. But didn't get nowhere. | 12:17 |
| amylaar_ | Oh, there was a review, but then I didn't really know the answer to a question. | 12:19 |
| amylaar_ | And ran out of time for the project. | 12:19 |
| amylaar_ | http://sourceware.org/ml/newlib/2012/msg00537.html | 12:19 |
| amylaar_ | And we still don't have enough time allocated for epiphany... | 12:20 |
| amylaar_ | Maybe you can pick this up for MAGEEC? | 12:20 |
| @simoncook | jamespallister: AWhetter: reading http://en.cppreference.com/w/c/numeric/random/rand under notes mentioning about some implementations having serious shortcomings in randomness, I would say there is no set algorithm, one rand is different to another | 12:21 |
| @simoncook | also, http://sourceware.org/git/?p=glibc.git;a=blob;f=stdlib/random_r.c;h=a393dd3c199b5b08a16f3044f2a3bc21f8e88410;hb=HEAD#l360 http://sourceware.org/git/?p=newlib.git;a=blob;f=newlib/libc/stdlib/rand_r.c;h=437739ef5a6a78a28a0d0089724fa6d5f2178ac9;hb=HEAD | 12:22 |
| jamespallister | Perhaps having a standard implementation of it would be useful then | 12:45 |
| jamespallister | for the benchmark suite | 12:45 |
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| AWhetter | I'll keep jrand for now then and add a better implementation to the TODO | 13:44 |
| @jeremybennett | AWhetter: I suggest if you want to use jrand, you should provide for it in platformcode.[ch] with a default implementation which calls rand. | 14:02 |
| AWhetter | I don't understand what you mean. I'd be using jrand so that I don't have to use rand. | 14:10 |
| @jeremybennett | So - we want these to work out of the box. | 14:23 |
| @jeremybennett | If you use jrand, then they will not compile out of the box, unless you provide a default implementation of jrand. | 14:24 |
| @jeremybennett | Are you proposing to provide that, and define it is the implementation that must be used? | 14:24 |
| @jeremybennett | Or are you going to allow the user to decide if they want to provide their own implementation? | 14:25 |
| @jeremybennett | If the former, then the implementation of jrand belongs in platformcode.c (assuming you are using the code structure I have in GitHub). | 14:25 |
| @jeremybennett | Otherwise you should provide just a default implementation of jrand and allow the user to change it. | 14:26 |
| @jeremybennett | In terms of code both are identical. It only affects what you put in the comments are README. | 14:26 |
| @jeremybennett | There is a minor wrinkle, that not being a library, jrand will be linked in whether you use it or not, so programs that do not use jrand will be slightly bigger than before. | 14:27 |
| AWhetter | oh ok. I'd already pulled platform code in from the other repository on my branch, but I see you've done the same so I'll merge it all together | 14:27 |
| @jeremybennett | You can get round the increased size issue by making jrand into a library that is linked against, but I wouldn't bother with that unless your implementation is very large. | 14:28 |
| @jeremybennett | At some stage I'll put an autotools infrastructure in to make building more standardized and maintainable. | 14:28 |
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| --- Log closed Fri Aug 02 00:00:44 2013 | ||
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