From d34a21fe21abe340057fd15330f16626a042df80 Mon Sep 17 00:00:00 2001
From: Oliver Sander <oliver.sander@tu-dresden.de>
Date: Sun, 22 Nov 2020 11:29:55 +0100
Subject: [PATCH] Implement addToDiagonal for scalars (interpreted as 1x1
matrices)
This is required for dune-istl matrices than use scalars to end
the nesting recursion (and not FieldMatrix), like BCRSMatrix<double>.
---
CHANGELOG.md | 4 +++-
dune/matrix-vector/addtodiagonal.hh | 8 ++++++++
dune/matrix-vector/test/staticmatrixtoolstest.cc | 10 ++++++++++
3 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4a5d1c7..c766858 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,8 @@
# Master (will become release 2.8)
-- ...
+- The method `addToDiagonal` can now also be called if the matrix is a scalar number type.
+ This is needed since nowadays scalar entries can end the nesting recursion of dune-istl
+ matrices.
## Deprecations and removals
diff --git a/dune/matrix-vector/addtodiagonal.hh b/dune/matrix-vector/addtodiagonal.hh
index 90ad152..56de2fa 100644
--- a/dune/matrix-vector/addtodiagonal.hh
+++ b/dune/matrix-vector/addtodiagonal.hh
@@ -11,6 +11,14 @@ namespace MatrixVector {
x[i][i] += a;
}
+ /** \brief Specialization for scalars (to be interpreted as 1x1 matrices) */
+ template <class Matrix>
+ static void addToDiagonal(Matrix& x, const Matrix& a)
+ {
+ static_assert(IsNumber<Matrix>::value, "Only scalars can be treated both as matrix and as number!");
+ x += a;
+ }
+
/*
the line
diff --git a/dune/matrix-vector/test/staticmatrixtoolstest.cc b/dune/matrix-vector/test/staticmatrixtoolstest.cc
index 368f523..b3566a5 100644
--- a/dune/matrix-vector/test/staticmatrixtoolstest.cc
+++ b/dune/matrix-vector/test/staticmatrixtoolstest.cc
@@ -35,6 +35,16 @@ private:
// SQUARE MATRICES
+ // scalars
+ {
+ FieldType scalarMatrix_x = 1,
+ scalarMatrix_check = 4;
+
+ addToDiagonal(scalarMatrix_x, scalar_a);
+
+ passed = passed and
+ myDiff(scalarMatrix_x, scalarMatrix_check) < 1e-12;
+ }
// case FM
{
Dune::FieldMatrix<FieldType, 2, 2> squareFieldMatrix_x = {{1, 2}, {3, 4}},
--
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