RE: Bug #45926

[Bill Maier <shufflesky at hotmail dot com>]

I understand about keeping the repository safe. I'll just send a gzipped tar file to your email address with the code changes for you to copy into your sandbox. I've been playing with this for a couple of days now and I believe the issue is fixed without any side effects. Besides the code change I also added a couple of tests to try out the changes.

-Bill

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> Subject: Re: Bug #45926
> To: gsl-discuss@sourceware.org; shufflesky@hotmail.com
> From: alken@colorado.edu
> Date: Thu, 19 Nov 2015 15:21:06 -0700
>
> Hi Bill,
>
> Thanks for your help on this. It would be great if you can make a
> patch to fix this, and I'll have a look. For now you can do an anonymous
> checkout of the gsl repository and work from there. We typically reserve
> write access to the git until we have a chance to look at someone's code
> to make sure its high quality, and also to make sure they're serious
> about contributing in the future. But in general I'm very grateful to
> have someone interested in becoming involved.
>
> Patrick
>
> On 11/17/2015 06:50 PM, Bill Maier wrote:
>> I've investigated bug #45929 "error in generalized hypergeometric function". The problem is in the
>> file specfunc/hyperg_2F1.c in the first function the file, hyperg_2F1_series(). There is a loop starting
>> at line 59 which is intended to converge to the solution, and within this loop is a check to insure the
>> loop is not executed more than 30000 times. This code is actually working and computing the correct
>> value, but the error terms del_pos and del_neg eventually get no smaller and so the loop executes the
>> full 30000 iterations and then reports GSL_EMAXITER error, even though it does have the correct
>> value calculated.
>>
>> I would fix this by saving the previous error terms and insuring they are becoming smaller with each
>> iteration. If they are not getting smaller, machine precision has been reached and the value can be
>> returned to the user. I can supply code or could check in myself through git if I can get access. I have
>> 30+ years of experience with C code and want to begin helping maintain GSL.
>>
>> By the way, when I do a git clone to get the code and then run ./autogen, it fails with message
>> "autoreconf: not found". Has this file been left out of the git repository?
>>
>> -Bill Maier
>