### Trigonometric Functions With Error Estimates

Function: double gsl_sf_sin_err (double x, double dx)
Function: int gsl_sf_sin_err_e (double x, double dx, gsl_sf_result * result)
  These routines compute the sine of an angle x with an associated absolute error dx, \sin(x \pm dx).

Function: double gsl_sf_cos_err (double x, double dx)
Function: int gsl_sf_cos_err_e (double x, double dx, gsl_sf_result * result)
  These routines compute the cosine of an angle x with an associated absolute error dx, \cos(x \pm dx).