Arabic Sciences and Philosophy

Al-Quhi and al-Sijzi on the perfect compass and the continuous drawing of conic sections

Roshdi Rashed a1
a1 Centre d'histoire des sciences et des philosophies arabes et médiévales, 7 rue Guy Môquet, B.P. no 8, 9 4801 Villejuif Cedex, France


From the second half of the 10th century, mathematicians developed a new chapter in the geometry of conic sections, dealing with the theory and practice of their continuous drawing. In this article, we propose to sketch the history of this chapter in the writings of al-Quhi and al-Sijzi. A hitherto unknown treatise by al-Sijzi - established, translated, and commented - has enabled us better to situate and understand the themes of this new research, and how it eventually approached the problem of the classification of curves in previously unknown terms.