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Re: [Bug-gsl] GSL special functions

From: Brian Gough
Subject: Re: [Bug-gsl] GSL special functions
Date: Tue, 12 Sep 2006 11:04:27 +0100
User-agent: Wanderlust/2.14.0 (Africa) Emacs/21.3 Mule/5.0 (SAKAKI)

At Tue, 12 Sep 2006 10:35:15 +0200,
Harald Moseby wrote:
> I have noticed a few anomalies in a few special funtions of GSL:
> 1) Both gsl_sf_zeta_int() and gsl_sf_zetam1_int() return zero at even 
> negative integers. gsl_sf_zetam1_int_e() should be modified.
> 2) gsl_sf_laguerre_n(10000001, 2.5, 2.5) returns a wrong answer; -1.5e6 
> insted of 1.5e6. laguerre_large_n() seems to return the correct answer 
> only when n is even. Multiply by -1 when n is odd? I don't know.
> 3) gsl_sf_hyperg_1F1(1.2, 1.1e-15, 1.5) returns a wrong answer. 
> hyperg_1F1_renorm_b0() seems incorrect. I have not been able to understand 
> the implementation of Abramowitz+Stegun 13.3.7.
> 4) hyperg_1F1_large2bm4a() does not give correct answers. The algorithm is 
> implemented correctly, but fails it's task when a in [-1, 1]. It seems to 
> me that a must be large negative for hyperg_1F1_large2bm4a() to produce 
> sensible results.

Thank you for the bug reports.

Can you just confirm which version of GSL you are using and on what

If you could also send example programs that demonstrate the problems,
so we can reproduce them easily, that would be much appreciated.

best regards,

Brian Gough
(GSL Maintainer)

Network Theory Ltd,
Commercial support for GSL --- http://www.network-theory.com/gsl/

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