Rational points on circles

Abstract

We solve the following problem. For a given rational circle $C$ passing through the rational points $p$, $q$, $r$ and a given angle $\alpha$, compute a rational point on $C$ whose angle at $C$ differs from $\alpha$ by a value of at most $\epsilon$. In addition, try to minimize the bit length of the computed point. This document contains the C++ program |rational_points_on_circle.c|. We use the literate programming tool |noweb| by Norman Ramsey