//dot product
var a = [1, 2, 3];
var b = [4, 5, 6];

assert _length(a) == _length(b), "a and b lengths are wrong";

var acc = 0;
for (var i = 0; i < _length(a); i++) {
	acc += _get(a, i) * _get(b, i);
}

assert acc == 32, "dot product failed";


//assume the args are matrices
fn matrix(first, second) {
	//get the matrix size
	var l1 = _length(first); //rows
	var l2 = _length(_get(first, 0)); //cols

	var l3 = _length(second); //rows
	var l4 = _length(_get(second, 0)); //cols

	//pre-allocate the matrix
	var row = [];
	for (var j = 0; j < l4; j++) {
		_push(row, 0);
	}

	var result = [];
	for (var i = 0; i < l1; i++) {
		_push(result, row);
	}

	//assign the values
	for (var i = 0; i < _length(first); i++) {
		//select each element of "first"
		var firstElement = _get(first, i);

		//for each element of second
		for (var i2 = 0; i2 < _length(second); i2++) {
			for (var j2 = 0; j2 < _length(_get(second, 0)); j2++) {

				var val = _get(_get(first, i), i2) * _get(_get(second, i2), j2);

				//TODO: needs better notation than this tmpRow variable
				var tmpRow = _get(result, i);
				_set(tmpRow, j2, val);
				_set(result, i, tmpRow);

				//result[ i ][ j2 ] += first[i][i2] * second[i2][j2]
			}
		}
	}

	return result;
}

//matrix multiply
var c = [[4], [5], [6]]; //this is a 3x1
var d = [[1, 2, 3]]; //this is a 1x3

// c x d = 3x3
// d x c = 1x1

assert matrix(c, d) == [[4,8,12],[5,10,15],[6,12,18]], "Matrix multiplication failed";

print "All good";