Check for floating inputs for remainder implementation

floating_check_remainder.cpp

#include <iostream>
#include <cmath>
#include <vector>

int main() {
    std::vector<std::vector<double>> samples { {-7.5, -3.}, {-7.7, 3.1}, {-5.5, 3.}, {3., -2.5}, {3., 2.}, {7.3, 2.2}, {7.5, -2.} };
    std::cout << "Output format: a rem b is: std::remainder, output before PR, output after PR\n";
    for(auto vec: samples) {
        double a = vec[0], b = vec[1];

        // Before https://github.com/pytorch/pytorch/pull/37758
        auto out_before = a - b * static_cast<int>(std::floor(a/b));

        // After https://github.com/pytorch/pytorch/pull/37758
        auto out_after = std::fmod(a, b);
        if ((out_after != 0) && ((b < 0) != (out_after < 0))) out_after += b;

        std::cout << a << " rem " << b << " is: " << std::remainder(a, b) <<  ", " <<
                out_before << ", " << out_after << '\n';
    }
}