— Function: double gsl_sf_lnsinh (double x)
— Function: int gsl_sf_lnsinh_e (double x, gsl_sf_result * result)

These routines compute \log(\sinh(x)) for x > 0.

— Function: double gsl_sf_lncosh (double x)
— Function: int gsl_sf_lncosh_e (double x, gsl_sf_result * result)

These routines compute \log(\cosh(x)) for any x.