Calculate standard deviation of integers with C# .NET

Here comes a simple extension method to calculate the standard deviation of a list of integers:

public static double GetStandardDeviation(this IEnumerable<int> values)
{
	double standardDeviation = 0;
	int[] enumerable = values as int[] ?? values.ToArray();
	int count = enumerable.Count();
	if (count > 1)
	{
		double avg = enumerable.Average();
		double sum = enumerable.Sum(d => (d - avg) * (d - avg));
		standardDeviation = Math.Sqrt(sum / count);
	}
	return standardDeviation;
}

Here’s how you can call this method:

List<int> ints = new List<int>() { 4, 7, 3, 9, 13, 90, 5, 25, 13, 65, 34, 76, 54, 12, 51, 23, 3, 1, 7 };
double stdev = ints.GetStandardDeviation();

View all various C# language feature related posts here.