From 53544b2cfa102a3027003631976079d65be74e68 Mon Sep 17 00:00:00 2001
From: Oliver Sander <oliver.sander@tu-dresden.de>
Date: Wed, 11 Sep 2019 11:11:30 +0200
Subject: [PATCH] Implement negation for dense vectors and matrices
In other words, with this patch you can now write
FieldVector<double, 3> a = {1,2,3};
FieldVector<double, 3> b = -a;
and similarly for matrices.
---
CHANGELOG.md | 5 +++++
dune/common/densematrix.hh | 13 +++++++++++++
dune/common/densevector.hh | 12 ++++++++++++
dune/common/test/fmatrixtest.cc | 9 +++++++++
dune/common/test/fvectortest.cc | 3 +++
5 files changed, 42 insertions(+)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b16fba5f6..bed3db0df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,11 @@
implementation in `dune-common` is automatically disabled, and the official
implementation from the standard library is used instead.
+- By popular demand, dense vectors and matrices like `FieldVector` and `FieldMatrix`
+ now have additional operators. In particular, there are
+ - Vector = - Vector
+ - Matrix = - Matrix
+
- There is now (finally!) a method `power` in the file `math.hh` that computes
powers with an integer exponent, and is usable in compile-time expressions.
The use of the old power methods in `power.hh` is henceforth discouraged.
diff --git a/dune/common/densematrix.hh b/dune/common/densematrix.hh
index b03bbb0b5..5e511e922 100644
--- a/dune/common/densematrix.hh
+++ b/dune/common/densematrix.hh
@@ -321,6 +321,19 @@ namespace Dune
return asImp();
}
+ //! Matrix negation
+ derived_type operator- () const
+ {
+ MAT result;
+ typedef typename decltype(result)::size_type size_type;
+
+ for (size_type i = 0; i < rows(); ++i)
+ for (size_type j = 0; j < cols(); ++j)
+ result[i][j] = - asImp()[i][j];
+
+ return result;
+ }
+
//! vector space subtraction
template <class Other>
derived_type &operator-= (const DenseMatrix<Other>& x)
diff --git a/dune/common/densevector.hh b/dune/common/densevector.hh
index 5c2bfacf7..e3951a312 100644
--- a/dune/common/densevector.hh
+++ b/dune/common/densevector.hh
@@ -448,6 +448,18 @@ namespace Dune {
return (z-=b);
}
+ //! Vector negation
+ derived_type operator- () const
+ {
+ V result;
+ typedef typename decltype(result)::size_type size_type;
+
+ for (size_type i = 0; i < size(); ++i)
+ result[i] = -asImp()[i];
+
+ return result;
+ }
+
//! \brief vector space add scalar to all comps
/**
we use enable_if to avoid an ambiguity, if the
diff --git a/dune/common/test/fmatrixtest.cc b/dune/common/test/fmatrixtest.cc
index 9c6adcf52..b92f16690 100644
--- a/dune/common/test/fmatrixtest.cc
+++ b/dune/common/test/fmatrixtest.cc
@@ -416,6 +416,15 @@ void test_matrix()
if (tmp.infinity_norm() > 1e-12)
DUNE_THROW(FMatrixError, "Return value of axpy() incorrect!");
}
+ // -Matrix
+ {
+ FM neg = -A;
+ FM ref = typename FM::field_type(-1) * A;
+
+ if ((neg-ref).infinity_norm() > 1e-12)
+ DUNE_THROW(FMatrixError, "Return value of operator-(matrix) incorrect!");
+ }
+
}
{
using std::abs;
diff --git a/dune/common/test/fvectortest.cc b/dune/common/test/fvectortest.cc
index bc411c081..455816d1f 100644
--- a/dune/common/test/fvectortest.cc
+++ b/dune/common/test/fvectortest.cc
@@ -102,6 +102,9 @@ struct FieldVectorMainTestCommons
w *= a;
w /= a;
+ // Negation
+ -v;
+
// test scalar product, axpy
a = v * w;
a = v.dot(w);
--
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