code: public double[] eigenToSampleSpace( double[] eigenData ) {
          if( eigenData.length != numComponents )
              throw new IllegalArgumentException("Unexpected sample length");
  
          DMatrixRMaj s = new DMatrixRMaj(A.getNumCols(),1);
          DMatrixRMaj r = DMatrixRMaj.wrap(numComponents,1,eigenData);
          
          CommonOps_DDRM.multTransA(V_t,r,s);
  
          DMatrixRMaj mean = DMatrixRMaj.wrap(A.getNumCols(),1,this.mean);
          CommonOps_DDRM.add(s,mean,s);
  
          return s.data;
      }
docs: Converts a vector from eigen space into sample space.
  
  @param eigenData Eigen space data.
  @return Sample space projection.