How did the lunar and command modules find each other during lunar orbit rendezvous

The orbit and space above the Moon is such an enormous place. How in the world did a tiny lunar module and a tiny command module manage to find each other, and link up for rendezvous, on those Apollo missions? How did they know where each other would be?

Basically the rendezvous parameters and launch of the ascent module time were worked out by computer. The ascent module had to have a fairly precise launch time, launch angle, and velocity in order to put it close to the command module. Radar also played a big role in the final approach. Once the ascent module had the command module on radar it was just a matter of literally flying it to rendezvous. By this time in manned spaceflight there had been so many rendezvous performed in space that it had become routine.

Yup, the mathematics of orbital dynamics and celestial dynamics to the rescue.
http://www.ams.org/bookstore/pspdf/cbms-…
http://code.google.com/p/virtualagc/wiki…
http://www.braeunig.us/space/orbmech.htm

Pretty cool stuff.

The same way the shuttles found the ISS or Soyuz rockets found Mir.
Radar on board the ships and ground-based tracking providing data.