Estimates the arithmetic sample mean and the unbiased population variance from the provided samples as enumerable sequence, in a single pass without memoization. On a dataset of size N will use an N-1 normalizer (Bessel's correction). Returns NaN for mean if data is empty or any entry is NaN, and NaN for variance if data has less than two entries or if any entry is NaN.

public static Tuple<double, double> MeanVariance(
	IEnumerable<double> samples
)