launchrv2oe(rv,vv,mu);

function oe = launchrv2oe(rv,vv,mu);
	K  = [0;0;1];
	hv = cross(rv,vv);
	nv = cross(K,hv);
	n  = sqrt(nv.'*nv);
	h2 = (hv.'*hv);
	v2 = (vv.'*vv);
	r  = sqrt(rv.'*rv);
	ev = 1/mu *( (v2-mu/r)*rv - (rv.'*vv)*vv );
	p  = h2/mu;
%
% now compute the oe's
%
	e  = sqrt(ev.'*ev);		% eccentricity
	a  = p/(1-e*e);			% semimajor axis
	i  = acos(hv(3)/sqrt(h2));	% inclination
	Om = acos(nv(1)/n);		% RAAN
	if ( nv(2) < 0-eps )		% fix quadrant
		Om = 2*pi-Om;
	end;
	om = acos(nv.'*ev/n/e);		% arg of periapsis
	if ( ev(3) < 0 )		% fix quadrant
		om = 2*pi-om;
	end;
	nu = acos(ev.'*rv/e/r);		% true anomaly
	if ( rv.'*vv < 0 )		% fix quadrant
		nu = 2*pi-nu;
	end;
	oe = [a e i Om om nu];		% assemble "vector"