Re: [Bug-gsl] bug: gsl_sf_bessel_zero_Jnu(double nu, unsigned int s)

[Brian Gough]

Michael Gilbert writes:
 > Hi,
 > 
 > If nu is negative, gsl_sf_bessel_zero_Jnu(nu, s) returns an error.  This 
 > is a  trivial because Jnu(-x, s) = Jnu(x, s), so to handle the issue i 
 > just do gsl_sf_bessel_zero_Jnu(fabs(x), s).  I think this would be an 
 > easy bug to fix.

Thanks for the bug report. I found the following comment in
the source code bessel_zero.c:

  else if(nu < 0.0) {
    /* This can be done, I'm just lazy now. */
    result->val = 0.0;
    result->err = 0.0;
    GSL_ERROR("unimplemented", GSL_EUNIMPL);
  }

Until there is an implementation I will update the
documentation to say that negative nu is not supported.

best regards,

-- 
Brian Gough

----------------------------------------------------------------------
Network Theory Ltd             Phone: +44 (0)117 3179309
15 Royal Park                    Fax: +44 (0)117 9048108
Bristol BS8 3AL                  WWW: http://www.network-theory.co.uk/
United Kingdom                 Email: address@hidden     
----------------------------------------------------------------------