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

[Alexey A. Illarionov]

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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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