/// <summary>
/// Estimates the sample mean and the unbiased population standard deviation from the provided samples.
/// On a dataset of size N will use an N-1 normalizer (Bessel's correction).
/// Returns NaN for mean if data is empty or if any entry is NaN and NaN for standard deviation if data has less than two entries or if any entry is NaN.
/// </summary>
/// <param name="samples">The data to calculate the mean of.</param>
/// <returns>The mean of the sample.</returns>
public static Tuple <double, double> MeanStandardDeviation(this IEnumerable <double> samples)
{
var array = samples as double[];
return(array != null
? ArrayStatistics.MeanStandardDeviation(array)
: StreamingStatistics.MeanStandardDeviation(samples));
}