]> https://gitweb.dealii.org/ - dealii-svn.git/commitdiff
Slight changes in comments.
authorkronbichler <kronbichler@0785d39b-7218-0410-832d-ea1e28bc413d>
Mon, 27 Oct 2008 13:32:22 +0000 (13:32 +0000)
committerkronbichler <kronbichler@0785d39b-7218-0410-832d-ea1e28bc413d>
Mon, 27 Oct 2008 13:32:22 +0000 (13:32 +0000)
git-svn-id: https://svn.dealii.org/trunk@17349 0785d39b-7218-0410-832d-ea1e28bc413d

deal.II/examples/step-27/doc/intro.dox
deal.II/examples/step-27/step-27.cc

index e019caef329851b9232873a22eeb279dccfb9247..54996363bb122e7111225cf3c98539f409b90eb7 100644 (file)
@@ -715,15 +715,14 @@ we now use the following:
                                    hanging_node_constraints, false);
 @endcode
 
-Note also the last argument <tt>false</tt> for the creation of the
-sparsity pattern. It tells the sparsity pattern that constrained
-entries should not be inserted into the sparsity pattern. This makes
-sense for the way we're going to do assembly, which does the
-elimination of constraints already locally. Hence, we will never write
-touch the constrained entries. This gives some additional performance
-gain, since the system matrix will use have less entries &mdash; this
-saves both memory and computing time when doing matrix-vector
-multiplications or using a preconditioner.
+Note the last <tt>false</tt> argument we pass when creating the sparsity
+pattern. It tells the sparsity pattern that constrained entries should not
+be inserted into the sparsity pattern. This makes sense for the way we're
+going to do assembly, which does the elimination of constraints already
+locally. Hence, we will never write touch the constrained entries. This is
+the second key to increase this program's performance, since the system
+matrix will have less entries &mdash; this saves both memory and computing
+time when doing matrix-vector multiplications or applying a preconditioner.
 
 In a similar vein, we have to slightly modify the way we copy local
 contributions into global matrices and vectors. In previous tutorial programs,
index ea13fc6048feefaae504f3ebde988c8fe652c30d..7fdbc93bf0c5ce7feb0f1ce228c9bdb67f6abac0 100644 (file)
@@ -211,27 +211,24 @@ LaplaceProblem<dim>::~LaplaceProblem ()
                                 // @sect4{LaplaceProblem::setup_system}
                                 //
                                 // This function is again an almost
-                                // verbatim copy of what we already
-                                // did in step-6, with the main
-                                // difference that we don't directly
-                                // build the sparsity pattern, but
-                                // first create an intermediate
-                                // object that we later copy into the
-                                // right data structure. In another
-                                // slight deviation, we do not first
-                                // build the sparsity pattern then
-                                // condense away constrained degrees
-                                // of freedom, but pass the
-                                // constraint matrix object directly
-                                // to the function that builds the
-                                // sparsity pattern. We disable the
-                                // insertion of constrained entries
-                                // with <tt>false</tt> as fourth
-                                // argument in the
-                                // DoFTools::make_sparsity_pattern
-                                // function. Both of these steps are
-                                // explained in the introduction of
-                                // this program.
+                                // verbatim copy of what we already did in
+                                // step-6, with the main difference that we
+                                // don't directly build the sparsity
+                                // pattern, but first create an
+                                // intermediate object that we later copy
+                                // into the right data structure. In
+                                // another slight deviation, we do not
+                                // first build the sparsity pattern then
+                                // condense away constrained degrees of
+                                // freedom, but pass the constraint matrix
+                                // object directly to the function that
+                                // builds the sparsity pattern. We disable
+                                // the insertion of constrained entries
+                                // with <tt>false</tt> as fourth argument
+                                // in the DoFTools::make_sparsity_pattern
+                                // function. Both of these changes are
+                                // explained in the introduction of this
+                                // program.
                                 //
                                 // The second change, maybe hidden in plain
                                 // sight, is that the dof_handler variable

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