$filename = "$animdir/frame_00${framenumber}.gif/gif" if ($framenumber<10);
    $filename = "$animdir/frame_0${framenumber}.gif/gif" if (($framenumber>9) and ($f
+ramenumber<100));
    $filename = "$animdir/frame_${framenumber}.gif/gif" if $framenumber>99;

##</code><code>##

   $filename = sprintf "%s/frame_%03d.gif/gif", $animdir, $framenumber;