boon/src/main/java/org/boon/primitive/Dbl.java
public static double varianceDouble(double[] values, final int start, final int length) {
        double mean = mean(values, start, length);
        double temp = 0;
        for(int index = start; index < length; index++) {
            double a = values[index];
            temp += (mean-a)*(mean-a);
        }
        return temp / length;
    }
public static double varianceDouble(double[] values, final int start, final int length) {
        double mean = mean(values, start, length);
        double temp = 0;
        for(int index = start; index < length; index++) {
            double a = values[index];
            temp += (mean-a)*(mean-a);
        }
        return temp / length;
    }
Calculate Variance.

@param values values
@param start start
@param length length
@return variance