Troesch, Albert Discrete straight lines and calendars. (Droites discrètes et calendriers.) (French) Zbl 1155.01348 Math. Inf. Sci. Hum. 141, 11-41 (1998). Summary: The structure of a calendar can be described by a sequence of quasi-affine forms. Such a sequence, that will be called quasi-affine basis, generalizes the notion of numeration basis. The problem of the date conversion is therefore reduced to the writing of the Julian Day in such a basis. A discrete straight line recognizing algorithm enables us to obtain the good quasi-affine basis. As examples are given the Julian, Gregorian, Islamic and Judaic calendars. MSC: 01A99 History of mathematics and mathematicians 00A08 Recreational mathematics PDFBibTeX XMLCite \textit{A. Troesch}, Math. Inf. Sci. Hum. 141, 11--41 (1998; Zbl 1155.01348) Full Text: Numdam EuDML Link