sig
external central : f:(float -> float) -> x:float -> h:float -> Fun.result
= "ml_gsl_deriv_central"
external forward : f:(float -> float) -> x:float -> h:float -> Fun.result
= "ml_gsl_deriv_forward"
external backward : f:(float -> float) -> x:float -> h:float -> Fun.result
= "ml_gsl_deriv_backward"
end