From f8c11b324d705301348c98d719560fd4dd30efbc Mon Sep 17 00:00:00 2001
From: Oliver Sander <sander@igpm.rwth-aachen.de>
Date: Thu, 12 Jan 2012 10:00:03 +0000
Subject: [PATCH] Make Rotation<T,3> friend, it needs the derivatives of the
arcus cosine
[[Imported from SVN: r8369]]
---
dune/gfe/unitvector.hh | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/dune/gfe/unitvector.hh b/dune/gfe/unitvector.hh
index 7be1a3da..060ef865 100644
--- a/dune/gfe/unitvector.hh
+++ b/dune/gfe/unitvector.hh
@@ -6,6 +6,9 @@
#include <dune/gfe/tensor3.hh>
+template <class T, int N>
+class Rotation;
+
/** \brief A unit vector in R^N
\tparam N Dimension of the embedding space
@@ -14,6 +17,9 @@
template <class T, int N>
class UnitVector
{
+ // Rotation<T,3> is friend, because it needs the various derivatives of the arccos
+ friend class Rotation<T,3>;
+
/** \brief Computes sin(x) / x without getting unstable for small x */
static T sinc(const T& x) {
return (x < 1e-4) ? 1 - (x*x/6) : std::sin(x)/x;
--
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