public void TestGetSigma()
{
// simulate a 64 bit hash and 14 bits for indexing
const int bitsToCount = 64 - 14;
Assert.Equal(51, CardinalityEstimator.GetSigma(0, bitsToCount));
Assert.Equal(50, CardinalityEstimator.GetSigma(1, bitsToCount));
Assert.Equal(47, CardinalityEstimator.GetSigma(8, bitsToCount));
Assert.Equal(1, CardinalityEstimator.GetSigma((ulong)(Math.Pow(2, bitsToCount) - 1), bitsToCount));
Assert.Equal(51, CardinalityEstimator.GetSigma((ulong)(Math.Pow(2, bitsToCount + 1)), bitsToCount));
}
