docs: public Instance filterInstance(Instance x) {
  
  
  		if(dataset==null){
  			initialize(x);
  		}		
  
  		double z_[] = new double[H+1];
  
  		int d = x.numAttributes() - 1; // suppose one class attribute (at the end)
  
  		for(int k = 0; k < H; k++) {
  			// for each hidden unit ...
  			double a_k = 0.; 								// k-th activation (dot product)
  			for(int j = 0; j < d; j++) {
  				a_k += (x.value(j) * W[k][j]);
  			}
  			z_[k] = (a_k > 0. ? a_k : 0.);				  // <------- can change threshold here
  		}
  		z_[H] = x.classValue();
  
  		Instance z = new InstanceImpl(x.weight(),z_);
  		z.setDataset(dataset);
  
  		return z;
  	}