Finish going over the setup functions.

git-svn-id: https://svn.dealii.org/trunk@24517 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-32/step-32.cc b/deal.II/examples/step-32/step-32.cc
index 3eb48a4b2c414258dc659f6a596cd1d69a63bf12..2acc15f20cab1d6eb3ecc47c11c6081e7a30a42f 100644 (file)
--- a/deal.II/examples/step-32/step-32.cc
+++ b/deal.II/examples/step-32/step-32.cc
@@ -2519,7 +2519,27 @@ namespace Step32
                                               temperature_relevant_partitioning);
     }
 
-//@todo work from here
+                                    // Following this, we can compute
+                                    // constraints for the solution vectors,
+                                    // including hanging node constraints and
+                                    // homogenous and inhomogenous boundary
+                                    // values for the Stokes and temperature
+                                    // fields. Note that as for everything
+                                    // else, the constraint objects can not
+                                    // hold <i>all</i> constraints on every
+                                    // processor. Rather, each processor
+                                    // needs to store only those that are
+                                    // actually necessary for correctness
+                                    // given that it only assembles linear
+                                    // systems on cells it owns. As discussed
+                                    // in the
+                                    // @ref distributed_paper "this paper",
+                                    // the set of constraints we need to know
+                                    // about is exactly the set of
+                                    // constraints on all locally relevant
+                                    // degrees of freedom, so this is what we
+                                    // use to initialize the constraint
+                                    // objects.
     {
       stokes_constraints.clear ();
       stokes_constraints.reinit (stokes_relevant_set);
@@ -2560,6 +2580,13 @@ namespace Step32
       temperature_constraints.close ();
     }
 
+                                    // All this done, we can then initialize
+                                    // the various matrix and vector objects
+                                    // to their proper sizes. At the end, we
+                                    // also record that all matrices and
+                                    // preconditioners have to be re-computed
+                                    // at the beginning of the next time
+                                    // step.
     setup_stokes_matrix (stokes_partitioning);
     setup_stokes_preconditioner (stokes_partitioning);
     setup_temperature_matrices (temperature_partitioning);