From 19e1ca32b85979ba66276b925e69d94be4994f18 Mon Sep 17 00:00:00 2001 From: Daniel Arndt Date: Fri, 25 May 2018 12:08:38 +0200 Subject: [PATCH] Add comment --- source/multigrid/mg_transfer_prebuilt.cc | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/source/multigrid/mg_transfer_prebuilt.cc b/source/multigrid/mg_transfer_prebuilt.cc index 8d2205bb4b..1fdc0ed803 100644 --- a/source/multigrid/mg_transfer_prebuilt.cc +++ b/source/multigrid/mg_transfer_prebuilt.cc @@ -311,6 +311,14 @@ MGTransferPrebuilt::build_matrices( mg_dof); dsp.reinit(0, 0); + // In the end, the entries in this object will only be real valued. + // Nevertheless, we have to take the underlying scalar type of the + // vector we want to use this class with. The global matrix the entries + // of this matrix are copied into has to be able to perform a + // matrix-vector multiplication and this is in general only implemented if + // the scalar type for matrix and vector is the same. Furthermore, + // copying entries between this local object and the global matrix is only + // implemented if the objects have the same scalar type. FullMatrix prolongation; // now actually build the matrices -- 2.39.5