/// <summary>
/// Returns the standard deviation between an index interval in a data series
/// </summary>
/// <param name="dataSeries">Data series</param>
/// <param name="startIndex">Start index</param>
/// <param name="endIndex">End index</param>
/// <returns>double</returns>
public static double GetStandardDeviation(this DataSeries dataSeries, int startIndex, int endIndex)
{
var variance = dataSeries.GetVariance(startIndex, endIndex);
return(Math.Sqrt(variance));
}