From: Peter Munch <peterrmuench@gmail.com>
Date: Mon, 21 Dec 2020 12:52:31 +0000 (+0100)
Subject: Work on MatrixFreeTools::compute_matrix
X-Git-Tag: v9.3.0-rc1~731^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bda8bf8961cb28372f3c216c14b6a1b6207040af;p=dealii.git

Work on MatrixFreeTools::compute_matrix
---

diff --git a/include/deal.II/matrix_free/tools.h b/include/deal.II/matrix_free/tools.h
index 8bd19d735e..d0b7f9d435 100644
--- a/include/deal.II/matrix_free/tools.h
+++ b/include/deal.II/matrix_free/tools.h
@@ -99,8 +99,8 @@ namespace MatrixFreeTools
 
   /**
    * Compute the matrix representation of a linear operator (@p matrix), given
-   * @p matrix_free and the local cell integral operation @p local_vmult. The
-   * vector is initialized to the right size in the function.
+   * @p matrix_free and the local cell integral operation @p local_vmult.
+   * Constrained entries on the diagonal are set to one.
    *
    * The parameters @p dof_no, @p quad_no, and @p first_selected_component are
    * passed to the constructor of the FEEvaluation that is internally set up.
@@ -731,10 +731,12 @@ namespace MatrixFreeTools
 
     matrix.compress(VectorOperation::add);
 
-    for (unsigned int i = 0; i < matrix.m(); ++i)
-      if (matrix.get_row_length(i) > 0 && matrix(i, i) == 0.0 &&
-          constraints.is_constrained(i))
-        matrix.add(i, i, 1);
+    for (auto &entry : matrix)
+      if (entry.row() == entry.column() && entry.value() == 0.0)
+        {
+          Assert(constraints.is_constrained(entry.row()), ExcNotImplemented());
+          entry.value() = 1.0;
+        }
   }
 
   template <typename CLASS,