public void Gaussian_ZeroRsq_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(0.5);
writer.Write(0.5);
var rng = new NotRandomFromBytes(mem.ToArray(), true);
var actual = rng.NextGaussian(); // should throw because rsq values are zero
}
public void Gaussian_KnownValue_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
var d1 = 0.25;
var d2 = 0.75;
writer.Write(d1);
writer.Write(d2);
var rng = new NotRandomFromBytes(mem.ToArray(), true);
var actual = rng.NextGaussian();
var r1 = d1 * 2 - 1;
var r2 = d2 * 2 - 1;
var rsq = r1 * r1 + r2 * r2;
var expected = r1 * Math.Sqrt(-2.0 * Math.Log(rsq) / rsq);
Assert.AreEqual(expected, actual);
}