APEX and STRETCH: A Practical Form for the Conic Arc

This paper presents formulae and results from a practical implementation of a conic arc specified in terms of its end‐points and other descriptors, based on the three numeric factors, bulge, shear and squash, described in an earlier paper. The parametric form for the derivative is given, from which are found the normals from a given point to the arc, and formulae for splitting off one or more parts from it. A method of chordal approximation for plotting purposes is also presented, and the effects of applying transformations are discussed.