From 3ea1c8e913307dce98e3f206974fd386958b01e7 Mon Sep 17 00:00:00 2001
From: Elias Pipping <elias.pipping@fu-berlin.de>
Date: Mon, 19 Dec 2011 14:53:26 +0100
Subject: [PATCH] Rescale for numerical stability
---
dune/tectonic/myblockproblem.hh | 10 +++++++---
src/TODO.org | 1 -
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/dune/tectonic/myblockproblem.hh b/dune/tectonic/myblockproblem.hh
index 6e43c2b1..06b05444 100644
--- a/dune/tectonic/myblockproblem.hh
+++ b/dune/tectonic/myblockproblem.hh
@@ -74,7 +74,11 @@ template <class MyConvexProblemTypeTEMPLATE> class MyBlockProblem {
double computeDampingParameter(VectorType const &u,
VectorType const &projected_v) const {
- VectorType const v = projected_v;
+ VectorType v = projected_v;
+
+ double const vnorm = v.two_norm();
+
+ v /= vnorm; // Rescale for numerical stability
VectorType tmp = problem.f;
problem.A.mmv(u, tmp);
@@ -94,8 +98,8 @@ template <class MyConvexProblemTypeTEMPLATE> class MyBlockProblem {
localA, localb, problem.phi, u, v);
int bisectionsteps = 0;
- Bisection bisection(0.0, 1.0, 1e-12, true, 0); // TODO
- return bisection.minimize(psi, 1.0, 0.0, bisectionsteps); // TODO
+ Bisection bisection(0.0, 1.0, 1e-12, true, 0); // TODO
+ return bisection.minimize(psi, vnorm, 0.0, bisectionsteps) / vnorm; // TODO
}
void assembleTruncate(VectorType const &u, Linearization &linearization,
diff --git a/src/TODO.org b/src/TODO.org
index 5e66a10c..60d0487b 100644
--- a/src/TODO.org
+++ b/src/TODO.org
@@ -1,3 +1,2 @@
-* check if v should be normalised by default
* use nested iteration to obtain better iteration to start with
* fix up octave bindings (low-pri)
--
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