module.exports = rotate

/**
 * Rotates a mat2 by the given angle
 *
 * @alias mat2.rotate
 * @param {mat2} out the receiving matrix
 * @param {mat2} a the matrix to rotate
 * @param {Number} rad the angle to rotate the matrix by
 * @returns {mat2} out
 */
function rotate(out, a, rad) {
  var a0 = a[0], a1 = a[1], a2 = a[2], a3 = a[3]
  var s = Math.sin(rad)
  var c = Math.cos(rad)
  out[0] = a0 *  c + a2 * s
  out[1] = a1 *  c + a3 * s
  out[2] = a0 * -s + a2 * c
  out[3] = a1 * -s + a3 * c
  return out
}