c' as
               follows:

                  <a href="pxfrm2_c.html">pxfrm2_c</a> ( fixref, ref,    trgepc, et, xform );
                  <a href="mxv_c.html">mxv_c</a>    ( xform,  srfvec, refvec            );


   phase       is the phase angle at `spoint', as seen from `obsrvr' at
               time `et'.  This is the angle between the spoint-obsrvr
               vector and the spoint-sun vector. Units are radians. The
               range of `phase' is [0, pi].

 
   solar       is the solar inci