A method for calculating standard deviations with Apex.

Apex: Standard Deviation Example

public class AdvancedMath 
{
	public static Double standardDeviation(Double[] numbers)
	{
		//determine the sum of the range of numbers
		Double sum = 0;
		for(Double d : numbers)
		{
			sum += d;
		}

		//determine the mean of the range of numbers
		Double mean = sum / numbers.size();

		//for each number subtract the mean and square the result
		Double squaredDifferencesSum = 0;
		for(Double d : numbers)
		{
			squaredDifferencesSum += Math.pow((d-mean), 2);
		}

		//determine the mean for the squared differences
		Double squaredDifferencesMean = squaredDifferencesSum / numbers.size();

		//determine the standard deviation
		Double standardDeviation = Math.sqrt(squaredDifferencesMean);

		return standardDeviation;
	}
}