public static TriCubicSpline zero(int nP, int mP, int lP){
        	if(nP<3 || mP<3 || lP<3)throw new IllegalArgumentException("A minimum of three x three x three data points is needed");
        	TriCubicSpline aa = new TriCubicSpline(nP, mP, lP);
        	return aa;
    	}