derivative df f fdf fval_and_derivative operator()

void multimin_fdf::df ( const gsl_vector *  x, void *  p, gsl_vector *  g  ) [static] Static function that is called by gsl to get derivatives of f. Parameters: x : GSL vector x where multidim function is evaluated. *p : void pointer to pass other information such a sparameters. g : GSL vector containing gradient of function