public void NotRandomDouble_Ratio_Test()
{
var mem = new MemoryStream();
using (var writer = new BinaryWriter(mem))
{
writer.Write((ulong)0);
writer.Write((ulong)0x4000_0000_0000_0000);
writer.Write((ulong)0x8000_0000_0000_0000);
writer.Write((ulong)0xc000_0000_0000_0000);
writer.Write((ulong)0xffff_ffff_ffff_ffff);
var notRandom = new NotRandomFromBytes(mem.ToArray());
var x = notRandom.NextDouble();
Assert.AreEqual(0.0, x);
x = notRandom.NextDouble();
Assert.AreEqual(0.25, x);
x = notRandom.NextDouble();
Assert.AreEqual(0.5, x);
x = notRandom.NextDouble();
Assert.AreEqual(0.75, x);
x = notRandom.NextDouble();
Assert.IsTrue(x < 1.0);
}
}
public void ScaleValue_64_Test()
{
// This is a little overloaded- it covers all the cases within ScaleValue(this
// Random, ulong)
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(ulong.MaxValue); // cause a biased number if maxValue is even
writer.Write(0x0000_0001_0000_0017);
var buf = mem.ToArray();
var rng = new NotRandomFromBytes(buf);
var rnga = rng.Aspect();
var actual = rnga.NextLong(0x10);
Assert.AreEqual(7, actual);
rng = new NotRandomFromBytes(buf); // start over
actual = (long)rng.ScaleValue(0x10L);
Assert.AreEqual(7, actual);
var zero = 0ul;
var z2 = zero.ScaleValue(1, ulong.MaxValue, out _);
Assert.AreEqual(zero, z2);
}
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 Random_double_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(1L << 63); // Exactly in the middle [0..uint.MaxValue+1]
var rng = new NotRandomFromBytes(mem.ToArray());
var rnga = rng.Aspect();
var actual = rnga.NextDouble();
Assert.AreEqual(0.5, actual);
}
public void Random_Next1a_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(uint.MaxValue);
var rng = new NotRandomFromBytes(mem.ToArray());
var rnga = rng.Aspect();
// now we have an Aspect wrapping exactly 4 0xff bytes . The Aspect's Next operation
// will request more bytes (as the first value will == int.MaxValue), and this time
// the stream will not fail.
var actual = rnga.Next(-1);
}
public void Random_Next0a_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(uint.MaxValue);
var rng = new NotRandomFromBytes(mem.ToArray());
var rnga = rng.Aspect();
// now we have an Aspect wrapping exactly 4 0xff bytes. This will cause the Aspect's
// Next operation to request more bytes (as the value will == int.MaxValue), and
// cause the stream to fail.
var actual = rnga.Next();
}
public void Random_Next2_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(uint.MaxValue); // will cause bias
writer.Write(uint.MaxValue - 1); // will be returned
var rng = new NotRandomFromBytes(mem.ToArray());
var rnga = rng.Aspect();
var actual = rnga.Next(int.MinValue, int.MaxValue);
var expected = int.MaxValue - 1;
Assert.AreEqual(expected, actual);
}
public void Random_Next1b_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(uint.MaxValue);
writer.Write(42);
var rng = new NotRandomFromBytes(mem.ToArray());
var rnga = rng.Aspect();
var actual = rnga.Next(30);
var expected = 42 % 30;
Assert.AreEqual(expected, actual);
}
public void Random_Next0b_Test()
{
var mem = new MemoryStream();
var writer = new BinaryWriter(mem);
writer.Write(uint.MaxValue);
writer.Write(5);
var rng = new NotRandomFromBytes(mem.ToArray());
var rnga = rng.Aspect();
// now we have an Aspect wrapping exactly 4 0xff bytes followed by 4 bytes equalling
// 5. The Aspect's Next operation will request more bytes (as the first value will
// == int.MaxValue), and this time the stream will not fail.
var actual = rnga.Next();
Assert.AreEqual(5, actual);
}
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);
}
