static void test_stdnormal_sw(RandomNumberGenerator &rng) {
    vector<double> samples(SHAPIRO_WILK_DF);
    size_t i;

    for (i = 0; i < samples.size(); i++)
	samples[i] = rng.stdnormal();
    assert(shapiro_wilk_test(samples));
}
 virtual double operator()(RandomNumberGenerator &rng) const {
     return rng.stdnormal();
 }