From 4e6b588b12e7573973a27e37985cc238da9a0f94 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maximilian=20H=C3=B6rl?=
<maximilian.hoerl@mathematik.uni-stuttgart.de>
Date: Wed, 20 May 2020 12:16:21 +0200
Subject: [PATCH] check for diagonal matrix in eigenvaluehelper
---
dune/mmdg/eigenvaluehelper.hh | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/dune/mmdg/eigenvaluehelper.hh b/dune/mmdg/eigenvaluehelper.hh
index 63bde0f..a3e9cf0 100644
--- a/dune/mmdg/eigenvaluehelper.hh
+++ b/dune/mmdg/eigenvaluehelper.hh
@@ -36,6 +36,13 @@ public:
static void eigenValues(const Dune::FieldMatrix<K, 2, 2>& matrix,
Dune::FieldVector<K, 2>& eigenvalues)
{
+ if ( std::abs(matrix[1][0]) < 1e-15 && std::abs(matrix[0][1]) < 1e-15 )
+ { //diagonal matrix
+ eigenvalues[0] = std::min(matrix[0][0], matrix[1][1]);
+ eigenvalues[1] = std::max(matrix[0][0], matrix[1][1]);
+ return;
+ }
+
using std::sqrt;
const K detM = matrix[0][0] * matrix[1][1] - matrix[1][0] * matrix[0][1];
const K p = 0.5 * (matrix[0][0] + matrix [1][1]);
--
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