Summary: "Based on Lawden's equation, semi-explicit,'iterative' Saturn guidance equations are derived, many were successfully flight tested on Saturn I and analyzed for the main Apollo mission and other applications applications."
Within the first 10 minutes of NASA's initial Saturn IB flight, the Instrument Unit (IU), nervecenter of America's mightiest launch vehicle, is designed to make more than 7 million calculations, sample vehicle calculations 100 times a minute, telemeter 3 million numbers back to Earth, and measure the performance of 300 pieces of equipment in the IU, S-IB, and S-IVB stages.