Re: [Bug-gsl] Error in Coulomb Wave Function Routines

[Brian Gough]

scott pratt writes:
 > I ran into a problem with your routines for calculating F_L and G_L, the
 > partial-wave solutions for the Coulomb problem. The functions are  
 > discontinuous,
 > as the functions flip signs for values of x~3.2 and x~5.8 in the  
 > example below.
 > 
 > I'm working with GSL 1.7
 > 
 > x ____ F(L=0)  G(L=0) ___  F(L=1) G(L=1) ___ F(L=2) G(L=2) ___
 > 3.15     0.016  -1.001     1.004  -0.312     0.955   0.699
 > 3.20     0.034   1.001    -0.987   0.357    -0.974  -0.661

Thanks for the bug report... I can confirm the problem, the sign
mysteriously flips starting around 3.2 in gsl_sf_coulomb_wave_FG_e in
the branch starting at line 1122. Unfortunately I don't know how to
fix it yet.

-- 
Brian Gough

Network Theory Ltd,
Publishing the GSL Manual --- http://www.network-theory.co.uk/gsl/manual/