function?rst?=?rv2orbElem（rsvs）
mus=398600;
%vec2orbElem?-?Convert?position?and?velocity?vectors?to?orbital?elements.
%??????vec2orbElem（rsvsmus）?converts?positions?（rs）?and?velocities?（vs）
%??????of?bodies?with?gravitational?parameters?（mus）?to?Keplerian?orbital
%??????elements.
%
%??????INPUTS:
%??????rs???????3n?x?1?stacked?initial?position?vectors:
%???????????????[r1（1）;r1（2）;r1（3）;r2（1）;r2（2）r2（3）;...;rn（1）;rn（2）;rn（3）]
%???????????????or?3?x?n?matrix?of?position?vecotrs.
%??????vs???????3n?x?1?stacked?initial?velocity?vectors?or?3?x?n?matrix
%??????mus??????gravitational?parameters?（G*m_i）?where?G?is?the
%???????????????gravitational?constant?and?m_i?is?the?mass?of?the?ith?body.
%???????????????if?all?vectors?represent?the?same?body?mus?may?be?a
%???????????????scalar.
%??????OUTPUTS:
%??????a????????semi-major?axes
%??????e????????eccentricities
%??????E????????eccentric?anomalies
%??????I????????inclinations
%??????omega????arguments?of?pericenter
%??????Omega????longitude