...It was used by the American Ephemeris and the Astronomical Almanac into the 1980's to compute the daily positions of the Sun. This Theory is a semi-analytic model which expresses quantities as a trigonometric series with numerical coefficients. This type of model
produces a compact computer function which has enough accuracy to be useful to most users. My goal is to create a model using C which will reproduce exactly the results published in the Astronomical Almanac for the years 1981, 1982 and 1983.