public double correlationZeroTime(double[] sign1, double[] sign2){
		double sum = 0.0;
		if(sign1.length == sign2.length)
			for(int i=0; i < sign1.length; i++)
				sum += (sign1[i] * sign2[i]);
		else System.out.println("The length of sign1 and sign2 is not the same.");
		return (sum<0.00001)?0:sum;
	}