public Beta(double alpha, double beta) throws ParameterException {
		if (alpha <= 0 || beta <= 0) {
			throw new ParameterException("Beta parameters alpha > 0, beta > 0");
		} else {
			gamma1 = new Gamma(alpha, 1);
			gamma2 = new Gamma(beta, 1);
			this.alpha = alpha;
			this.beta = beta;
		}
		
	}