The following code shows how the main program uses it to display the standard deviations for the list of integers named values.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public static class StatsStuff
{
    // Return the standard deviation of an array of Doubles.
    //
    // If the second argument is True, evaluate as a sample.
    // If the second argument is False, evaluate as a population.
    public static double StdDev(this IEnumerable<int> values, bool as_sample)
    {
        // Get the mean.
        double mean = values.Sum() / values.Count();

        // Get the sum of the squares of the differences between
        // the values and the mean.
        var squares_query = (from int value in values select (value - mean) * (value - mean));
        double sum_of_squares = squares_query.Sum();

        if (as_sample)
        {
            return Math.Sqrt(sum_of_squares / (values.Count() - 1));
        }
        else
        {
            return Math.Sqrt(sum_of_squares / values.Count());
        }
    }
}