function scale$3(out, a, b) {
    out[0] = a[0] * b;
    out[1] = a[1] * b;
    out[2] = a[2] * b;
    out[3] = a[3] * b;
    return out;
  }
Scales a vec4 by a scalar number

@param {vec4} out the receiving vector
@param {ReadonlyVec4} a the vector to scale
@param {Number} b amount to scale the vector by
@returns {vec4} out