Listing 2.  The Weighted Variance Calculation
static uint variance(uint tw, uint tt_sum,
		uint t_ur, uint t_ug, uint t_ub)
{
	double temp;

	temp  = (double)t_ur * (double)t_ur;
	temp += (double)t_ug * (double)t_ug;
	temp += (double)t_ub * (double)t_ub;
	temp /= (double)tw;

	return ((uint)((double)tt_sum - temp));
}
