Point out DoFTools::extract_constant_modes

diff --git a/include/deal.II/lac/trilinos_precondition.h b/include/deal.II/lac/trilinos_precondition.h
index 1c5ae1061d95e55489e95ce7306f4fcfe3437f14..42f9a5b259fa3fe1d43079dc3865c05ea47c82e3 100644 (file)
--- a/include/deal.II/lac/trilinos_precondition.h
+++ b/include/deal.II/lac/trilinos_precondition.h
@@ -1510,6 +1510,8 @@ namespace TrilinosWrappers
        *       degree of freedom that is part of vector component <tt>ic</tt>.
        * </li>
        * </ul>
+       * We obtain the <tt>constant_modes</tt> fulfilling the above requirements
+       * with the function DoFTools::extract_constant_modes.
        */
       std::vector<std::vector<bool>> constant_modes;