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Re: tolerance in binopdf.m
From: |
Ben Abbott |
Subject: |
Re: tolerance in binopdf.m |
Date: |
Wed, 21 Sep 2011 11:25:32 -0400 |
On Sep 21, 2011, at 11:01 AM, Marco atzeri wrote:
> On 9/21/2011 3:07 PM, Ben Abbott wrote:
>>
>> On Sep 21, 2011, at 1:59 AM, Jordi Gutiérrez Hermoso wrote:
>>
>>> Just for fun, I asked someone to run this program on a Macintosh:
>>>
>>> #include<stdio.h>
>>> #include<math.h>
>>>
>>> int main()
>>> {
>>> printf("%0.100f\n",lgamma(3.0));
>>> }
>>>
>>> It turns out it does run, i.e. it does have an lgamma implementation.
>>> However, the exact value it outputs is 390207173010335/2^49, while on
>>> my Debian system, the exact value it outputs is
>>> 31216573840826795/2^52. It seems that somewhere along the way, 3 bits
>>> of precision were lost on the Macintosh.
>>>
>>> So I don't think there's anything we can do other than increase the
>>> tolerance by 3 bits to account for this. We already increase tolerance
>>> slightly for other systems for other tests.
>>>
>>> HTH,
>>> - Jordi G. H.
>>
>> Thanks for all the quick replies. From config.log I see ...
>>
>> | #define HAVE_LGAMMA 1
>> | #define HAVE_LGAMMAF 1
>> | #define HAVE_LGAMMA_R 1
>> | #define HAVE_LGAMMAF_R 1
>>
>> Thus, it looks to me as if Apple has a different implementation of lgamma
>> (?).
>>
>> As this is not a bug in Octave, I'm inclined to add a tolerance for MaOS.
>>
>> However, I'm curious about what Apple did.
>>
>> I'm using Xcode 4.1. The sources are below.
>>
>> http://www.opensource.apple.com/
>>
>> Does anyone have an idea of where to look to find the sources for lgamma?
>>
>> Ben
>>
>
> Could be here ?
>
> http://opensource.apple.com/source/Libm/
> http://opensource.apple.com/source/Libm/Libm-2026/Source/Intel/xmm_erfgamma.c
>
> Regards
> Marco
Yes, that is it!
Ben
- Re: tolerance in binopdf.m, (continued)
- Re: tolerance in binopdf.m, Rik, 2011/09/21
- Re: tolerance in binopdf.m, Marco Atzeri, 2011/09/21
- Re: tolerance in binopdf.m, Jordi Gutiérrez Hermoso, 2011/09/21
- Re: tolerance in binopdf.m, Michael D Godfrey, 2011/09/21
- Re: tolerance in binopdf.m, Michael D Godfrey, 2011/09/21
- Re: tolerance in binopdf.m, Ben Abbott, 2011/09/21
- Re: tolerance in binopdf.m, Ben Abbott, 2011/09/21
- Re: tolerance in binopdf.m, Marco atzeri, 2011/09/21
- Re: tolerance in binopdf.m,
Ben Abbott <=
- Re: tolerance in binopdf.m, Jordi Gutiérrez Hermoso, 2011/09/21
- Re: tolerance in binopdf.m, Dr. Alexander Klein, 2011/09/21
Re: Overhaul of statistical distribution functions, Michael D Godfrey, 2011/09/21
Re: Overhaul of statistical distribution functions, Michael D Godfrey, 2011/09/21