[Help-gsl] definition of dilogarithm in GSL

[Paul Zimmermann]

       Hi,

we are about the implement a dilogarithm function in MPFR. Looking at the
different definitions, it seems the GSL definition is not the "standard"
one in the Abramowitz&Stegun sense, but more what is commonly designed as
Li2(x) [as the GSL manual admits it].

This is quite annoying, since if we introduce a function mpfr_dilog in
MPFR, it will be either inconsistent with A&S, or inconsistent with GSL,
and in both cases will probably confuse the users.

One solution would be for us to only export a function mpfr_li2, which would
correspond to the "common" definition of Li2(x), and to the gsl_sf_dilog
function.

Would that be ok for you? Can you explain why you choosed that mathematical
definition for gsl_sf_dilog, or that name instead of gsl_sf_li2?

Best regards,
Paul Zimmermann
(for the MPFR developers)