From c757f4f7d02bf401c6317fd3b6d93d8d2b066b91 Mon Sep 17 00:00:00 2001
From: Jonathan Youett <youett@mi.fu-berlin.de>
Date: Thu, 3 Nov 2011 17:48:37 +0000
Subject: [PATCH] redo the interpolation-bug-patch
[[Imported from SVN: r8110]]
---
dune/gfe/rotation.hh | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/dune/gfe/rotation.hh b/dune/gfe/rotation.hh
index 1f00b6ed..b1d8ec3a 100644
--- a/dune/gfe/rotation.hh
+++ b/dune/gfe/rotation.hh
@@ -528,7 +528,12 @@ public:
diff.invert();
diff = diff.mult(b);
-
+
+ // Make sure we do the right thing if a and b are not in the same sheet
+ // of the double covering of the unit quaternions over SO(3)
+ if (dist>=M_PI)
+ diff *= -1;
+
// Compute the geodesical distance between a and b on SO(3)
// Due to numerical dirt, diff[3] may be larger than 1.
// In that case, use 1 instead of diff[3].
@@ -555,7 +560,14 @@ public:
} else {
T dist = 2*std::acos( diff[3] );
-
+
+ // Make sure we do the right thing if a and b are not in the same sheet
+ // of the double covering of the unit quaternions over SO(3)
+ if (dist>=M_PI) {
+ dist -= M_PI;
+ diff *= -1;
+ }
+
T invSinc = 1/sincHalf(dist);
// Compute difference on T_a SO(3)
--
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