public class ArrayStats{
 
    public static double mean (double[] ar){
	double sum = 0;
	for (double element : ar)
	    sum += element;
	return sum / ar.length;
    }

    public static double sd (double[] ar){
	double sum = 0, m = mean(ar);
	for (double element : ar)
	    sum += Math.pow (element - m, 2);
	return Math.sqrt(sum);
    }

}