code: @Nonnull
    public Matrix getU ()
    {
      final Matrix aNewMatrix = new Matrix (m_nCols, m_nCols);
      final double [] [] aNewArray = aNewMatrix.internalGetArray ();
      for (int nRow = 0; nRow < m_nCols; nRow++)
      {
        final double [] aSrcRow = m_aLU[nRow];
        final double [] aDstRow = aNewArray[nRow];
        for (int nCol = 0; nCol < m_nCols; nCol++)
          if (nRow <= nCol)
            aDstRow[nCol] = aSrcRow[nCol];
          else
            aDstRow[nCol] = 0.0;
      }
      return aNewMatrix;
    }
docs: Return upper triangular factor
  
  @return U