Function multiply

circletext/code.ts:9–14

(a, b)

// The first transform applied is a, followed by b, which
// is normally written b * a.
function multiply(a, b) {
  return [
    [ a[0][0] * b[0][0] + a[0][1] * b[1][0], a[0][0] * b[0][1] + a[0][1] * b[1][1], a[0][0] * b[0][2] + a[0][1] * b[1][2] + a[0][2] ],
    [ a[1][0] * b[0][0] + a[1][1] * b[1][0], a[1][0] * b[0][1] + a[1][1] * b[1][1] + 0, a[1][0] * b[0][2] + a[1][1] * b[1][2] + a[1][2] ]
  ]
}

// Creates a "move" transform.
function move(x, y) {