Typografowie, programiści i matematycy, czyli przypadek estetycznie zadowalającej interpolacji

The reason for preparing this report is that the author has been convinced or many years that John D. Hobby’s algorithm or connecting Bézier segments, implemented by Donald E. Knuth in METAFONT and later transferred by Hobby to METAPOST, based on the notion o a “mock curvature”, is a genuine pearl which deserves both proper acknowledgement and a far wider awareness of its existence. Of course, one can find nearly all the necessary details in the relevant papers by Hobby and in the METAFONT source, but, needless to say, it is not easy to dig through the publications. The present paper provides a full mathematical description of Hobby’s interpolation algorithm, discusses its advantages and disadvantages (in particular, its instability) and compares Hobby’s approach with a few selected simpler approaches.