From 2cface63514acc1f02214407bd50144ae6eccef0 Mon Sep 17 00:00:00 2001
From: Oliver Sander <sander@igpm.rwth-aachen.de>
Date: Thu, 5 Apr 2012 17:31:54 +0000
Subject: [PATCH] Do not recompute _every_ entry matrix entries, but only the
ones with i<=j. The rest follows from symmetry of the Hessian.
Needless to say, this makes the Hessian assembly quite
a bit faster.
[[Imported from SVN: r8587]]
---
dune/gfe/localgeodesicfestiffness.hh | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/dune/gfe/localgeodesicfestiffness.hh b/dune/gfe/localgeodesicfestiffness.hh
index d1aa6bd4..411cec4b 100644
--- a/dune/gfe/localgeodesicfestiffness.hh
+++ b/dune/gfe/localgeodesicfestiffness.hh
@@ -163,10 +163,12 @@ assembleHessian(const Entity& element,
std::vector<TargetSpace> forwardSolutionXiEta = localSolution;
std::vector<TargetSpace> backwardSolutionXiEta = localSolution;
+ // we loop over the lower left triangular half of the matrix.
+ // The other half follows from symmetry
for (size_t i=0; i<localSolution.size(); i++) {
for (size_t i2=0; i2<blocksize; i2++) {
- for (size_t j=0; j<localSolution.size(); j++) {
- for (size_t j2=0; j2<blocksize; j2++) {
+ for (size_t j=0; j<=i; j++) {
+ for (size_t j2=0; j2<((i==j) ? i2+1 : blocksize); j2++) {
Dune::FieldVector<double,embeddedBlocksize> epsXi = B[i][i2]; epsXi *= eps;
Dune::FieldVector<double,embeddedBlocksize> epsEta = B[j][j2]; epsEta *= eps;
@@ -191,7 +193,7 @@ assembleHessian(const Entity& element,
double forwardValue = energy(element, localFiniteElement, forwardSolutionXiEta) - forwardEnergy[i][i2] - forwardEnergy[j][j2];
double backwardValue = energy(element, localFiniteElement, backwardSolutionXiEta) - backwardEnergy[i][i2] - backwardEnergy[j][j2];
- A_[i][j][i2][j2] = 0.5 * (forwardValue - 2*centerValue + backwardValue) / (eps*eps);
+ A_[i][j][i2][j2] = A_[j][i][j2][i2] = 0.5 * (forwardValue - 2*centerValue + backwardValue) / (eps*eps);
// Restore the forwardSolutionXiEta and backwardSolutionXiEta variables.
// They will both be identical to the 'solution' array again.
--
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