Fmod is a math function to perform a modulus operation on doubles.
std::modf has a different purpose as Fmod: std::modf splits a double into its integer and a fractional part, for example it splits 12.34 into 12 and 0.34
#include <cassert> double Fmod(const double x, const double mod) { assert(mod != 0.0); //Cannot divide by zero return x - (mod * static_cast<int>(x / mod)); }