func Backward(f *gogsl.GslFunction, x float64, h float64) (int32, float64, float64) {
var _outptr_3 C.double
var _outptr_4 C.double
gogsl.InitializeGslFunction(f)
_result := int32(C.gsl_deriv_backward((*C.gsl_function)(unsafe.Pointer(f.CPtr())), C.double(x), C.double(h), &_outptr_3, &_outptr_4))
return _result, *(*float64)(unsafe.Pointer(&_outptr_3)), *(*float64)(unsafe.Pointer(&_outptr_4))
}
// Diff computes the derivative of ff, returns derivative and an error
func Diff(dir DerivType, ff gslgo.F, x, h float64) (gslgo.Result, error) {
var y, err C.double
var ret C.int
var gf C.gsl_function
data := gslgo.GSLFuncWrapper{ff}
gf = C.mkderivCB(unsafe.Pointer(&data))
switch dir {
case Central:
ret = C.gsl_deriv_central(&gf, C.double(x), C.double(h), &y, &err)
case Forward:
ret = C.gsl_deriv_forward(&gf, C.double(x), C.double(h), &y, &err)
case Backward:
ret = C.gsl_deriv_backward(&gf, C.double(x), C.double(h), &y, &err)
default:
panic(errors.New("Unknown direction"))
}
if ret != 0 {
return gslgo.Result{float64(y), float64(err)}, gslgo.Errno(ret)
}
return gslgo.Result{float64(y), float64(err)}, nil
}