matrix multiplication

gistfile1.txt

	Mat.mul = function (a, b) {
 		var r 	= Mat.identity(),
			rm 	= Mat.identity();


		rm[0] = a[0] * b[0];
		rm[1] = a[1] * b[4];
		rm[2] = a[2] * b[8];
		rm[3] = a[3] * b[12];

		r[0] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[1] * b[0];
		rm[1] = a[5] * b[1];
		rm[2] = a[9] * b[2];
		rm[3] = a[13] * b[3];

		r[1] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[0] * b[2];
		rm[1] = a[1] * b[6];
		rm[2] = a[2] * b[10];
		rm[3] = a[3] * b[14];

		r[2] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[0] * b[3];
		rm[1] = a[1] * b[7];
		rm[2] = a[2] * b[11];
		rm[3] = a[3] * b[15];

		r[3] = rm[0] + rm[1] + rm[2] + rm[3];


		rm[0] = a[4] * b[0];
		rm[1] = a[5] * b[4];
		rm[2] = a[6] * b[8];
		rm[3] = a[7] * b[12];

		r[4] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[4] * b[1];
		rm[1] = a[5] * b[5];
		rm[2] = a[6] * b[9];
		rm[3] = a[7] * b[13];

		r[5] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[4] * b[2];
		rm[1] = a[5] * b[6];
		rm[2] = a[6] * b[10];
		rm[3] = a[7] * b[14];

		r[6] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[4] * b[3];
		rm[1] = a[5] * b[7];
		rm[2] = a[6] * b[11];
		rm[3] = a[7] * b[15];

		r[7] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[8] * b[0];
		rm[1] = a[9] * b[4];
		rm[2] = a[10] * b[8];
		rm[3] = a[11] * b[12];

		r[8] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[8] * b[1];
		rm[1] = a[9] * b[5];
		rm[2] = a[10] * b[9];
		rm[3] = a[11] * b[13];

		r[9] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[8] * b[2];
		rm[1] = a[9] * b[6];
		rm[2] = a[10] * b[10];
		rm[3] = a[11] * b[14];

		r[10] = rm[0] + rm[1] + rm[2] + rm[3];


		rm[0] = a[8] * b[3];
		rm[1] = a[9] * b[7];
		rm[2] = a[10] * b[11];
		rm[3] = a[11] * b[15];

		r[11] = rm[0] + rm[1] + rm[2] + rm[3];


		rm[0] = a[12] * b[0];
		rm[1] = a[13] * b[4];
		rm[2] = a[14] * b[8];
		rm[3] = a[15] * b[12];

		r[12] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[12] * b[1];
		rm[1] = a[13] * b[5];
		rm[2] = a[14] * b[9];
		rm[3] = a[15] * b[13];

		r[13] = rm[0] + rm[1] + rm[2] + rm[3];

		rm[0] = a[12] * b[2];
		rm[1] = a[13] * b[6];
		rm[2] = a[14] * b[10];
		rm[3] = a[15] * b[14];

		r[14] = rm[0] + rm[1] + rm[2] + rm[3];


		rm[0] = a[12] * b[3];
		rm[1] = a[13] * b[7];
		rm[2] = a[14] * b[11];
		rm[3] = a[15] * b[15];

		r[15] = rm[0] + rm[1] + rm[2] + rm[3];


		return r;
	};