function clone(a) {
  var out = new glMatrix.ARRAY_TYPE(6);
  out[0] = a[0];
  out[1] = a[1];
  out[2] = a[2];
  out[3] = a[3];
  out[4] = a[4];
  out[5] = a[5];
  return out;
}
Creates a new mat2d initialized with values from an existing matrix

@param {mat2d} a matrix to clone
@returns {mat2d} a new 2x3 matrix