public static function Atciq($rc, $dc, $pr, $pd, $px, $rv, iauASTROM $astrom,
          &$ri, &$di) {

    $pco  = [];
    $pnat = [];
    $ppr  = [];
    $pi   = [];
    $w;

    /* Proper motion and parallax, giving BCRS coordinate direction. */
    IAU::Pmpx($rc, $dc, $pr, $pd, $px, $rv, $astrom->pmt, $astrom->eb, $pco);

    /* Light deflection by the Sun, giving BCRS natural direction. */
    IAU::Ldsun($pco, $astrom->eh, $astrom->em, $pnat);

    /* Aberration, giving GCRS proper direction. */
    IAU::Ab($pnat, $astrom->v, $astrom->em, $astrom->bm1, $ppr);

    /* Bias-precession-nutation, giving CIRS proper direction. */
    IAU::Rxp($astrom->bpn, $ppr, $pi);

    /* CIRS RA,Dec. */
    IAU::C2s($pi, $w, $di);
    $ri = IAU::Anp($w);

    /* Finished. */
  }