extension of specfunc/debye.c

[Brian Gough]

Richard Mathar writes:
 > a) The description in the HTML manual on the Chebyshev Approximations
 > in http://www.gnu.org/software/gsl/manual/gsl-ref_28.html#SEC413
 > is slightly out of date, because in the typedef struct {...} gsl_cheb_struct
 > the last component of the structure, int order_sp, is missing. Also,
 > it seems that this is know called gsl_series_struct, not gsl_cheb_struct (?).
 > 
 > b) Since the standard application of the Debye function with black body
 > radiation "starts" a power of n=3, and the current implementation in
 > specfunc/debye.c and specfunc/gsl_sf_debye.h reaches only to n=4, this
 > is somewhat too short if one wants to compile moments over black body functions.
 > Therefore I propose to extend the implementation to n=5 and n=6,
 > as in the implementation attached.

Thanks for the bug report and extra functions!  I will add those in
the next release. Sorry for the delay in replying.

-- 
Brian Gough