code: public double response( double[] sample ) {
          if( sample.length != A.numCols )
              throw new IllegalArgumentException("Expected input vector to be in sample space");
  
          DMatrixRMaj dots = new DMatrixRMaj(numComponents,1);
          DMatrixRMaj s = DMatrixRMaj.wrap(A.numCols,1,sample);
  
          CommonOps_DDRM.mult(V_t,s,dots);
  
          return NormOps_DDRM.normF(dots);
      }
docs: Computes the dot product of each basis vector against the sample.  Can be used as a measure
  for membership in the training sample set.  High values correspond to a better fit.
  
  @param sample Sample of original data.
  @return Higher value indicates it is more likely to be a member of input dataset.