INTERSECTPLANESPHERE Return intersection circle between a plane and a sphere.

   CIRC = intersectPlaneSphere(PLANE, SPHERE)
   Returns the circle which is the intersection of the given plane
   and sphere. 
   PLANE  : [x0 y0 z0  dx1 dy1 dz1  dx2 dy2 dz2]
   SPHERE : [XS YS ZS  RS]
   CIRC   : [XC YC ZC  RC  THETA PHI PSI]
   [x0 y0 z0] is the origin of the plane, [dx1 dy1 dz1] and [dx2 dy2 dz2]
   are two direction vectors,
   [XS YS ZS] are coordinates of the sphere center, RS is the sphere
   radius, 
   [XC YC ZC] are coordinates of the circle center, RC is the radius of
   the circle, [THETA PHI] is the normal of the plane containing the
   circle (THETA being the colatitude, and PHI the azimut), and PSI is a
   rotation angle around the normal (equal to zero in this function, but
   kept for compatibility with other functions). All angles are given in
   degrees.
   
   See Also:
   planes3d, spheres, circles3d, intersectLinePlane, intersectLineSphere

   ---------
   author : David Legland 
   INRA - TPV URPOI - BIA IMASTE
   created the 18/02/2005.

Package: matgeom