PROGRAM ANGLECALC - This program uses the equations developed in this book to calculate the sun altitude angle (Eqn. 3.17), sun zenith angle (Eqn. 3.8) and sun azimuth angle (Eqn. 3.19). Also, with input of the collector (or tracking axis) tilt angle and tilt azimuth, we calculate the angle of incidence between the sun rays and the collector aperture (Eqns. 4.3, 4.19, and 4.24.). We use Eqn.(3.22) to calculate the sunset and sunrise time, and then Eqn.(3.23) to calculate the hours of sunshine for the day.