... Abstract Convert a CSPICE ellipse to a center vector and two generating vectors. ... The set of ellipse conversion routines is cgv2el_c ( Center and generating vectors to ellipse ) el2cgv_c ( Ellipse to center and generating vectors ) A word about the output of this routine: the semi-major axis of an ellipse is a vector of largest possible magnitude in the set cos(theta) vec1 + sin(theta) vec2, where theta is in the interval (-pi, pi]. ... Index_Entries ellipse to center and generating vectors . ...