From 3352f104815be206fdeaec508244c9e10e13f54b Mon Sep 17 00:00:00 2001
From: Nils-Arne Dreier <n.dreier@uni-muenster.de>
Date: Wed, 9 Feb 2022 17:31:44 +0100
Subject: [PATCH] [amg] fix w-cycle
---
dune/istl/paamg/amg.hh | 8 +++++++-
dune/istl/paamg/test/amgtest.cc | 22 ++++++++++++++++------
2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/dune/istl/paamg/amg.hh b/dune/istl/paamg/amg.hh
index 1e05f663e..3825ce851 100644
--- a/dune/istl/paamg/amg.hh
+++ b/dune/istl/paamg/amg.hh
@@ -1057,8 +1057,14 @@ namespace Dune
if(processNextLevel) {
// next level
- for(std::size_t i=0; i<gamma_; i++)
+ for(std::size_t i=0; i<gamma_; i++){
mgc(levelContext);
+ if (levelContext.matrix == matrices_->matrices().coarsest() && levels()==maxlevels())
+ break;
+ if(i+1 < gamma_){
+ levelContext.matrix->applyscaleadd(-1., *levelContext.lhs, *levelContext.rhs);
+ }
+ }
}
moveToFineLevel(levelContext, processNextLevel);
diff --git a/dune/istl/paamg/test/amgtest.cc b/dune/istl/paamg/test/amgtest.cc
index b8dbd0e9a..c7e1843a0 100644
--- a/dune/istl/paamg/test/amgtest.cc
+++ b/dune/istl/paamg/test/amgtest.cc
@@ -77,7 +77,7 @@ void randomize(const M& mat, V& b)
template <class Matrix, class Vector>
-void testAMG(int N, int coarsenTarget, int ml)
+Dune::InverseOperatorResult testAMG(int N, int coarsenTarget, int ml, int gamma = 1)
{
std::cout<<"N="<<N<<" coarsenTarget="<<coarsenTarget<<" maxlevel="<<ml<<std::endl;
@@ -139,6 +139,7 @@ void testAMG(int N, int coarsenTarget, int ml)
criterion.setDefaultValuesIsotropic(2);
criterion.setAlpha(.67);
criterion.setBeta(1.0e-4);
+ criterion.setGamma(gamma);
criterion.setMaxLevel(ml);
criterion.setSkipIsolated(false);
// specify pre/post smoother steps
@@ -176,6 +177,7 @@ void testAMG(int N, int coarsenTarget, int ml)
std::cout<<"CG solving took "<<watch.elapsed()<<" seconds"<<std::endl;
*/
+ return r;
}
@@ -195,11 +197,19 @@ try
if(argc>3)
ml = atoi(argv[3]);
- {
- using Matrix = Dune::BCRSMatrix<XREAL>;
- using Vector = Dune::BlockVector<XREAL>;
-
- testAMG<Matrix,Vector>(N, coarsenTarget, ml);
+ Dune::InverseOperatorResult gamma1_res;
+ for(int gamma = 1; gamma<=2;++gamma){
+ {
+ using Matrix = Dune::BCRSMatrix<XREAL>;
+ using Vector = Dune::BlockVector<XREAL>;
+
+ Dune::InverseOperatorResult res = testAMG<Matrix,Vector>(N, coarsenTarget, ml, gamma);
+ if(gamma==1){
+ gamma1_res = res;
+ }else{
+ assert(res.conv_rate < gamma1_res.conv_rate);
+ }
+ }
}
{
--
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