From 1152c35fa8e55083b70be75fc7c2e7e5293f07b9 Mon Sep 17 00:00:00 2001
From: Oliver Sander <sander@igpm.rwth-aachen.de>
Date: Thu, 3 Jan 2013 09:38:03 +0000
Subject: [PATCH] Factor computation of first derivatives of F wrt to its 2nd
argument into a separate method
[[Imported from SVN: r9092]]
---
dune/gfe/hyperbolichalfspacepoint.hh | 46 ++++++++++++----------------
1 file changed, 20 insertions(+), 26 deletions(-)
diff --git a/dune/gfe/hyperbolichalfspacepoint.hh b/dune/gfe/hyperbolichalfspacepoint.hh
index c6302d53..679c3ab1 100644
--- a/dune/gfe/hyperbolichalfspacepoint.hh
+++ b/dune/gfe/hyperbolichalfspacepoint.hh
@@ -48,6 +48,21 @@ class HyperbolicHalfspacePoint
}
}
+ /** \brief Compute derivative of $F(p,q) = 1 + ||p-q||^2 / 2p_nq_n with respect to q
+ \param[in] diffNormSquared Expected to be ||p-q||^2, taken from the caller for efficiency reasons
+ */
+ static Dune::FieldVector<T,N> computeDFdq(const HyperbolicHalfspacePoint& p, const HyperbolicHalfspacePoint& q, const T& diffNormSquared)
+ {
+ Dune::FieldVector<T,N> result;
+
+ for (size_t i=0; i<N-1; i++)
+ result[i] = ( q.data_[i] - p.data_[i] ) / (q.data_[N-1] * p.data_[N-1]);
+
+ result[N-1] = - diffNormSquared / (2*p.data_[N-1]*q.data_[N-1]*q.data_[N-1]) - (p.data_[N-1] - q.data_[N-1]) / (p.data_[N-1]*q.data_[N-1]);
+
+ return result;
+ }
+
public:
/** \brief The type used for coordinates */
@@ -141,17 +156,12 @@ public:
*/
static EmbeddedTangentVector derivativeOfDistanceSquaredWRTSecondArgument(const HyperbolicHalfspacePoint& a, const HyperbolicHalfspacePoint& b) {
- TangentVector result;
-
T diffNormSquared(0);
for (size_t i=0; i<N; i++)
diffNormSquared += (a.data_[i]-b.data_[i])*(a.data_[i]-b.data_[i]);
- for (size_t i=0; i<N-1; i++)
- result[i] = ( b.data_[i] - a.data_[i] ) / (a.data_[N-1] * b.data_[N-1]);
-
- result[N-1] = - diffNormSquared / (2*a.data_[N-1]*b.data_[N-1]*b.data_[N-1]) - (a.data_[N-1] - b.data_[N-1]) / (a.data_[N-1]*b.data_[N-1]);
+ TangentVector result = computeDFdq(a,b,diffNormSquared);
T x = 1 + diffNormSquared/ (2*a.data_[N-1]*b.data_[N-1]);
@@ -173,11 +183,7 @@ public:
T diffNormSquared = (p-q).two_norm2();
// Compute first derivative of F
- Dune::FieldVector<T,N> dFdq;
- for (size_t i=0; i<N-1; i++)
- dFdq[i] = ( b.data_[i] - a.data_[i] ) / (a.data_[N-1] * b.data_[N-1]);
-
- dFdq[N-1] = - diffNormSquared / (2*a.data_[N-1]*b.data_[N-1]*b.data_[N-1]) - (a.data_[N-1] - b.data_[N-1]) / (a.data_[N-1]*b.data_[N-1]);
+ Dune::FieldVector<T,N> dFdq = computeDFdq(a,b,diffNormSquared);
// Compute second derivatives of F
Dune::FieldMatrix<T,N,N> dFdqdq;
@@ -240,11 +246,7 @@ public:
dFdp[N-1] = - diffNormSquared / (2*p[N-1]*q[N-1]*q[N-1]) - (p[N-1] - q[N-1]) / (p[N-1]*q[N-1]);
- Dune::FieldVector<T,N> dFdq;
- for (size_t i=0; i<N-1; i++)
- dFdq[i] = ( q[i] - p[i] ) / (p[N-1] * q[N-1]);
-
- dFdq[N-1] = - diffNormSquared / (2*p[N-1]*q[N-1]*q[N-1]) - (p[N-1] - q[N-1]) / (p[N-1]*q[N-1]);
+ Dune::FieldVector<T,N> dFdq = computeDFdq(a,b,diffNormSquared);
// Compute second derivatives of F
Dune::FieldMatrix<T,N,N> dFdpdq;
@@ -305,11 +307,7 @@ public:
T diffNormSquared = (p-q).two_norm2();
// Compute first derivative of F
- Dune::FieldVector<T,N> dFdq;
- for (size_t i=0; i<N-1; i++)
- dFdq[i] = ( b.data_[i] - a.data_[i] ) / (a.data_[N-1] * b.data_[N-1]);
-
- dFdq[N-1] = - diffNormSquared / (2*a.data_[N-1]*b.data_[N-1]*b.data_[N-1]) - (a.data_[N-1] - b.data_[N-1]) / (a.data_[N-1]*b.data_[N-1]);
+ Dune::FieldVector<T,N> dFdq = computeDFdq(a,b,diffNormSquared);
// Compute second derivatives of F
Dune::FieldMatrix<T,N,N> dFdqdq;
@@ -428,11 +426,7 @@ public:
dFdp[N-1] = - diffNormSquared / (2*p[N-1]*q[N-1]*q[N-1]) - (p[N-1] - q[N-1]) / (p[N-1]*q[N-1]);
- Dune::FieldVector<T,N> dFdq;
- for (size_t i=0; i<N-1; i++)
- dFdq[i] = ( b.data_[i] - a.data_[i] ) / (a.data_[N-1] * b.data_[N-1]);
-
- dFdq[N-1] = - diffNormSquared / (2*a.data_[N-1]*b.data_[N-1]*b.data_[N-1]) - (a.data_[N-1] - b.data_[N-1]) / (a.data_[N-1]*b.data_[N-1]);
+ Dune::FieldVector<T,N> dFdq = computeDFdq(a,b,diffNormSquared);
// Compute second derivatives of F
Dune::FieldMatrix<T,N,N> dFdqdq;
--
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