code: public Mat4 subtract(final Mat4 right) {
              return new Mat4(
                              m00 - right.m00, m01 - right.m01, m02 - right.m02, m03 - right.m03,
                              m10 - right.m10, m11 - right.m11, m12 - right.m12, m13 - right.m13,
                              m20 - right.m20, m21 - right.m21, m22 - right.m22, m23 - right.m23,
                              m30 - right.m30, m31 - right.m31, m32 - right.m32, m33 - right.m33
              );
          }
docs: Subtract other matrix from this one and return the result ( this - right )
  @param right