docs: public SimpleMatrix getR() {
          SimpleMatrix R = new SimpleMatrix(QR.numRows(),QR.numCols());
  
          int N = Math.min(QR.numCols(),QR.numRows());
  
          for( int i = 0; i < N; i++ ) {
              for( int j = i; j < QR.numCols(); j++ ) {
                  R.set(i,j, QR.get(i,j));
              }
          }
  
          return R;
      }