[Help-gsl] Wolfram EllipticK vs gsl_sf_ellint_Kcomp

[Ruben Van Boxem]

Hi,

Since recently I have been using GSL for the odd mathematical functions that
appear in my calculations.

I am using the library, compiled with and for mingw-w64
(x86_64-w64-mingw32), and BesselK functions work nicely.

Today I needed Wolfram's
EllipticK<http://www.wolframalpha.com/input/?i=EllipticK%28.1%29>,
but GSL outputs the wrong value.

I'm comparing GSL's

> gsl_sf_ellint_Kcomp
>
with Wolfram's EllipticK<http://www.wolframalpha.com/input/?i=EllipticK%28.1%29>

GSL: 1.6564411200033
Wolfram: 1.6124413487

GCC version is 4.4.5 (prerelease).

I am currently building GSL for the i686-w64-mingw32 target, and wonder if
I'll get the same result.

Of course it's possible that I used the wrong GSL function, but the
documentation seems to match Wolfram's definition of EllipticK.

Thanks for any help!