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#############################################################
## ##
## Copyright (c) 2003-2011 by The University of Queensland ##
## Earth Systems Science Computational Centre (ESSCC) ##
## http://www.uq.edu.au/esscc ##
## ##
## Primary Business: Brisbane, Queensland, Australia ##
## Licensed under the Open Software License version 3.0 ##
## http://www.opensource.org/licenses/osl-3.0.php ##
## ##
#############################################################
"""
Common function and class definitions.
"""
import math
from esys.lsm.vis import core
def computeRotateWxyz(v1, v2):
"""
Returns the angle (in degrees) and axis of rotation required
to rotate v1 onto v2.
@type v1: sequence of 3 floats
@param v1: Vector to be rotated.
@type v2: sequence of 3 floats
@param v2: C{v1} rotated parallel to this vector.
@rtype: tuple
@return: C{(angle, axis)} rotation which rotates C{v1} parallel to C{v2}.
"""
vv1 = core.Vec3(v1)
vv2 = core.Vec3(v2)
theta = (math.acos(vv2.dot(vv1)/(vv2.norm()*vv1.norm())))*(180.0/math.pi)
rotAxis = vv2.cross(vv1)
return (theta, rotAxis/(-(rotAxis.norm())))
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