protected CohoNumber nextNorm(CohoMatrix A_trans_base, Matrix x, Matrix y, CohoNumber currNorm){
		try{
			Matrix pi = A_trans_base.getSolution(x);
			Matrix eta = A_trans_base.getSolution(y); 
			CohoNumber newNorm = null;
			for(int i=0;i<pi.length();i++){
				CohoNumber pi_i = pi.V(i);
				CohoNumber eta_i = eta.V(i);
				if(eta_i.compareTo(0.0)<0 && pi_i.compareTo(0.0)>=0){//pi_i must be non-negative here. Otherwise, it's not optimal basis
					CohoNumber Norm_i = pi_i.div(eta_i.negate());//positive
					if(	(newNorm==null ||(newNorm!=null && Norm_i.compareTo(newNorm)<0)) 
							&& Norm_i.compareTo(currNorm)>0){//is it possible norm_i<currNorm
						newNorm = Norm_i;
					}
				}
			}
			return newNorm;//return null if next quad
		}catch(SingularMatrixException e){
			throw new LPError("LPproject.nextNorm(): This should never happen when solve the optimal point.");
		}
	}