public static double StandardDeviation(double[][] num, int col)
	{
		double Sum = 0.0, SumOfSqrs = 0.0;
		int len = num[0].length;
		for (int i = 0; i < len; i++)
		{
			Sum += num[i][col];
			SumOfSqrs += Math.pow(num[i][col], 2);
		}
		double topSum = (len * SumOfSqrs) - (Math.pow(Sum, 2));
		double n = (double) len;
		return Math.sqrt(topSum / (n * (n - 1)));
	}