Evaluates the population covariance from the full population provided as two enumerable sequences, in a single pass without memoization. On a dataset of size N will use an N normalizer and would thus be biased if applied to a subset. Returns NaN if data is empty or if any entry is NaN.

public static double PopulationCovariance(
	IEnumerable<double> population1,
	IEnumerable<double> population2
)