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improper rotation matrix from pdecomposition could cause negative arguments in squareroot

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Franz Roters 2011-03-03 10:47:07 +00:00
parent 6667e94238
commit e7c7ccdcdd
1 changed files with 11 additions and 7 deletions
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code/math.f90
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@ -1376,18 +1376,22 @@ pure function math_transpose3x3(A)
real(pReal), dimension (3,3), intent(in) :: R
real(pReal), dimension(4) :: absQ,math_RtoQuaternion
real(pReal) max_absQ
integer(pInt), dimension(1) :: largest
! math adopted from http://code.google.com/p/mtex/source/browse/trunk/geometry/geometry_tools/mat2quat.m
math_RtoQuaternion = 0.0_pReal
absQ(1) = 0.5_pReal * sqrt(1.0_pReal+R(1,1)+R(2,2)+R(3,3))
absQ(2) = 0.5_pReal * sqrt(1.0_pReal+R(1,1)-R(2,2)-R(3,3))
absQ(3) = 0.5_pReal * sqrt(1.0_pReal-R(1,1)+R(2,2)-R(3,3))
absQ(4) = 0.5_pReal * sqrt(1.0_pReal-R(1,1)-R(2,2)+R(3,3))
absQ(1) = 1.0_pReal+R(1,1)+R(2,2)+R(3,3)
absQ(2) = 1.0_pReal+R(1,1)-R(2,2)-R(3,3)
absQ(3) = 1.0_pReal-R(1,1)+R(2,2)-R(3,3)
absQ(4) = 1.0_pReal-R(1,1)-R(2,2)+R(3,3)
largest = maxloc(absQ)
max_absQ=0.5_pReal * sqrt(absQ(largest(1)))
select case(largest(1))
case (1)
@ -1414,8 +1418,8 @@ pure function math_transpose3x3(A)
end select
math_RtoQuaternion = math_RtoQuaternion*0.25_pReal/maxval(absQ)
math_RtoQuaternion(largest(1)) = maxval(absQ)
math_RtoQuaternion = math_RtoQuaternion*0.25_pReal/max_absQ
math_RtoQuaternion(largest(1)) = max_absQ
return