public static double frechetCDF(double mu, double sigma, double gamma, double lowerlimit, double upperlimit) {
		double arg1 = (lowerlimit - mu) / sigma;
		double arg2 = (upperlimit - mu) / sigma;
		double term1 = 0.0D, term2 = 0.0D;
		if (arg1 >= 0.0D) term1 = Math.exp(-Math.pow(arg1, -gamma));
		if (arg2 >= 0.0D) term2 = Math.exp(-Math.pow(arg2, -gamma));
		return term2 - term1;
	}