Re: [Bug-gsl] problem in cubic solver

[Brian Gough]

At Tue, 28 Apr 2009 17:11:31 +0200,
Lorenzo Moneta wrote:
>   I have found a problem with solver for cubic equation (both complex  
> and real one)
>   In some particular case a NaN is returned, as shown in the attached  
> text example.
> The problem is observed mainly on 64 bit architectures (for example  
> Linux 64-bit  with gcc 4.3)  and not on 32 bit architectures.
> 
> This is due to a problem in a sqrt. A patch is attached fixing the  
> problem for the complex routine (gsl_poly_complex_solve_cubic ).
> A similar patch can be probably done also for the real routine
> 
>   This patch fails the current test for polynomial in gsl, however in  
> my opinion, this is acceptable, because the test condition is too  
> strict. With a slight change of the test coefficient, you will have a  
> similar failure also with the current version.

Thanks for the bug report and patch, I will look at that.

-- 
Brian Gough