From 8ab101da50a3f631716cec7c01fb0d63163496c6 Mon Sep 17 00:00:00 2001
From: Christoph	Kords <c.kords@mpie.de>
Date: Thu, 29 Apr 2010 10:33:39 +0000
Subject: [PATCH] safe use of acos function in math_QuaternionToAxisAngle

---
 code/math.f90 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/code/math.f90 b/code/math.f90
index 596f04c9c..e826cdecd 100644
--- a/code/math.f90
+++ b/code/math.f90
@@ -1386,7 +1386,7 @@ pure function math_transpose3x3(A)
  real(pReal) halfAngle, sinHalfAngle
  real(pReal), dimension(4) :: math_QuaternionToAxisAngle  
 
- halfAngle = dacos(Q(1))                             ! value range 0 to 180 deg
+ halfAngle = dacos(max(-1.0_pReal, min(1.0_pReal, Q(1))))                             ! value range 0 to 180 deg
  sinHalfAngle = dsin(halfAngle)
  
  if (sinHalfAngle <= 1.0e-4_pReal) then             ! very small rotation angle?