From: Daniel Arndt Date: Fri, 25 May 2018 10:08:38 +0000 (+0200) Subject: Add comment X-Git-Tag: v9.1.0-rc1~1097^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F6662%2Fhead;p=dealii.git Add comment --- 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