mat4: float det() const

Return the determinant of the matrix.

The determinant of a mat4 is calculated this way:

\(\scriptsize det = x.x * (y.y * z.z * w.w - y.y * w.z * z.w - z.y * y.z * w.w + z.y * w.z * y.w + w.y * y.z * z.w - w.y * z.z * y.w) -\) \(\scriptsize y.x * (x.y * z.z * w.w - x.y * w.z * z.w - z.y * x.z * w.w + z.y * w.z * x.w + w.y * x.z * z.w - w.y * z.z * x.w) +\) \(\scriptsize z.x * (x.y * y.z * w.w - x.y * w.z * y.w - y.y * x.z * w.w + y.y * w.z * x.w + w.y * x.z * y.w - w.y * y.z * x.w) -\) \(\scriptsize w.x * (x.y * y.z * z.w - x.y * z.z * y.w - y.y * x.z * z.w + y.y * z.z * x.w + z.y * x.z * y.w - z.y * y.z * x.w)\)

Example

#include "include/mat4.h"
#include <iostream>

int main() {
        nml::mat4 m(1.0f, 2.0f, 4.0f, 8.0f, 16.0f, 32.0f, 64.0f, 8.0f, 9.0f, 10.0f, 11.0f, 12.0f, 13.0f, 14.0f, 15.0f, 16.0f);
        std::cout << m.det() << std::endl;

        return 0;
}

Result:

480