public static double StandardDeviation(IEnumerable‹double› sequence)
{
    var computation = (Count: 0, Sum: 0.0, SumOfSquares: 0.0);

    foreach (var item in sequence)
    {
        computation.Count++;
        computation.Sum += item;
        computation.SumOfSquares += item * item;
    }

var variance = computation.SumOfSquares - computation.Sum * computation.Sum / computation.Count;
return Math.Sqrt(variance / computation.Count);
}