function normalize$3(out, a) {
    var x = a[0];
    var y = a[1];
    var z = a[2];
    var w = a[3];
    var len = x * x + y * y + z * z + w * w;

    if (len > 0) {
      len = 1 / Math.sqrt(len);
    }

    out[0] = x * len;
    out[1] = y * len;
    out[2] = z * len;
    out[3] = w * len;
    return out;
  }
Normalize a vec4

@param {vec4} out the receiving vector
@param {ReadonlyVec4} a vector to normalize
@returns {vec4} out