@cindex Jacobi elliptic functions
@cindex elliptic functions (Jacobi)

The Jacobian Elliptic functions are defined in Abramowitz & Stegun,
Chapter 16.  The functions are declared in the header file
@file{gsl_sf_elljac.h}.

@deftypefun int gsl_sf_elljac_e (double @var{u}, double @var{m}, double * @var{sn}, double * @var{cn}, double * @var{dn})
This function computes the Jacobian elliptic functions @math{sn(u|m)},
@math{cn(u|m)}, @math{dn(u|m)} by descending Landen
transformations.
@comment Exceptional Return Values: GSL_EDOM
@end deftypefun