From: Guido Kanschat <dr.guido.kanschat@gmail.com>
Date: Thu, 24 Mar 2005 16:53:31 +0000 (+0000)
Subject: Fix debug output and eliminate redundant coarse level solve
X-Git-Tag: v8.0.0~14315
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c606c3339aacf9e9ef16a0a4b669b95c00234024;p=dealii.git

Fix debug output and eliminate redundant coarse level solve


git-svn-id: https://svn.dealii.org/trunk@10231 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/deal.II/include/multigrid/multigrid.templates.h b/deal.II/deal.II/include/multigrid/multigrid.templates.h
index 5cacf07327..e3ddccfcb5 100644
--- a/deal.II/deal.II/include/multigrid/multigrid.templates.h
+++ b/deal.II/deal.II/include/multigrid/multigrid.templates.h
@@ -198,6 +198,14 @@ void
 Multigrid<VECTOR>::level_step(const unsigned int level,
 			      Cycle cycle)
 {
+  char cychar = '?';
+  switch (cycle)
+    {
+      case v_cycle: cychar = 'V'; break;
+      case f_cycle: cychar = 'F'; break;
+      case w_cycle: cychar = 'W'; break;
+    }
+  
 				   // Not actually the defect yet, but
 				   // we do not want to spend yet
 				   // another vector.
@@ -217,13 +225,13 @@ Multigrid<VECTOR>::level_step(const unsigned int level,
   if (level == minlevel)
     {
       if (debug>0)
-	deallog << "W-cycle solving  level " << level << std::endl;
+	deallog << cychar << "-cycle solving  level " << level << std::endl;
   
       (*coarse)(level, solution[level], t[level]);
       return;
     }
   if (debug>0)
-    deallog << "W-cycle entering level " << level << std::endl;
+    deallog << cychar << "-cycle entering level " << level << std::endl;
   
   if (debug>1)
     deallog << "Smoothing on     level " << level << std::endl;
@@ -250,14 +258,20 @@ Multigrid<VECTOR>::level_step(const unsigned int level,
 				   // here for the sake of the
 				   // F-cycle, needs only one,
   level_step(level-1, cycle);
-				   // while the W-cycle repeats itself
-  if (cycle == w_cycle)
-    level_step(level-1, cycle);
-				   // and the F-cycle does a V-cycle
-				   // after an F-cycle.
-  else if (cycle == f_cycle)
-    level_step(level-1, v_cycle);
-
+				   // If we solve exactly, then we do
+				   // not need a second coarse grid
+				   // step.
+  if (level>minlevel+1)
+    {
+				       // while the W-cycle repeats itself
+      if (cycle == w_cycle)
+	level_step(level-1, cycle);
+				       // and the F-cycle does a V-cycle
+				       // after an F-cycle.
+      else if (cycle == f_cycle)
+	level_step(level-1, v_cycle);
+    }
+  
 				   // reset size of the auxiliary
 				   // vector, since it has been
 				   // resized in the recursive call to
@@ -282,7 +296,7 @@ Multigrid<VECTOR>::level_step(const unsigned int level,
   post_smooth->smooth(level, solution[level], t[level]);
 
   if (debug>1)
-    deallog << "W-cycle leaving  level " << level << std::endl;
+    deallog << cychar << "-cycle leaving  level " << level << std::endl;
 }