Re: [Bug-gsl] Error in coulomb.c

[Patrick Alken]

This domain of arguments is for x > 2*eta, but in test_coulomb.c there 
are several tests in this range of arguments which seem to pass ok.

On 06/19/2013 07:56 PM, Alexey A. Illarionov wrote:
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> Hi,
>
> Nope, I did not. I will try to look closer to this on weekend, but I
> doubt that we could obtain reliable values in that domain of arguments.
>
>
> Patrick Alken wrote:
> > Hi, thanks for the report. Do you have an example of calling the
> > gsl_sf_coulomb_wave_FG_e function with input arguments that lead to
> > the wrong output? This would be useful in making test cases for
> > this issue.
> >
> > Patrick
> >
> > On 06/18/2013 11:58 PM, Alexey A. Illarionov wrote: Accidentally
> > found a bug in specfun/coulomb.c . Trivial error in solution of
> > quadratic equation. None of the current test cases are influenced
> > by this bug since the value of C (actually N) determines only the
> > condition of applicability of "continued fraction+recursion"
> > algorithm.
> >
> > === modified file 'specfunc/coulomb.c' --- specfunc/coulomb.c
> > 2007-07-02 18:34:24 +0000 +++ specfunc/coulomb.c    2012-10-26
> > 04:27:18 +0000 @@ -1121,7 +1121,7 @@ *           we must go at
> > least as low as lam_G */ const double SMALL =
> > GSL_SQRT_DBL_EPSILON; -    const double C = sqrt(1.0 +
> > 4.0*x*(x-2.0*eta)); +    const double C = 0.5 * sqrt(1.0 +
> > 4.0*x*(x-2.0*eta)); const int N = ceil(lam_F - C + 0.5); const
> > double lam_0   = lam_F - GSL_MAX(N, 0); const double lam_min =
> > GSL_MIN(lam_0, lam_G);
> >
> > -- С уважением, Алексей Александрович Илларионов.
> - -- 
> С уважением, Алексей Александрович Илларионов.
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