rovide an outward surface
                    normal.
                    ./
                    <a href="ilumin_c.html">ilumin_c</a> ( &quot;Ellipsoid&quot;, target, et,     fixref,
                               abcorr,      obsrvr, xpt,    &amp;etrgep,
                               esrfvc,      &amp;phase, &amp;solar, &amp;emissn );

                    printf ( 
                    &quot;            Illumination angles derived using an\n&quot;
                    &quot;            ellipsoidal reference