Paul de Casteljau (19 November 1930 – 24 March 2022) was a French physicist and mathematician. In 1959, while working at Citroën, he developed an algorithm for evaluating calculations on a certain family of curves, which would later be formalized and popularized by engineer Pierre Bézier, leading to the curves widely known as Bézier curves. He studied at École Normale Supérieure, and worked at Citroën from 1958 until his retirement in 1992. When he arrived there, "Specialists admitted that all electrical, electronic and mechanical problems had more or less been solved. All—except for one single formality which made up for 5%, but certainly not for 20% of the problem; in other words, how to express component parts by equations." A short autobiographic sketch goes back to the early 1990s, a longer autobiography talks about his education and life at Citroën until his retirement. He continued publishing in retirement, which led to three monographs and ten academic papers, most of his publications written in French.

De Casteljau curves

De Casteljau's algorithm is widely used, with some modifications, as it is the most robust and numerically stable method for evaluating polynomials. Other methods, such as Horner's method and forward differencing, are faster for calculating single points but are less robust. De Casteljau's algorithm is still very fast for subdividing a De Casteljau curve or Bézier curve into two curve segments at an arbitrary parametric location.

Further contributions

Noteworthy are his contributions beyond geometric modeling, which only became known internationally posthumously

Awards

Paul de Casteljau received the 1987 Seymour Cray Prize from the French National Center for Scientific Research, the 1993 John Gregory Memorial Award, and the 2012 Bézier Award from the Solid Modeling Association (SMA). The SMA's announcement highlights de Casteljau's eponymous algorithm: The SMA also quotes Pierre Bézier on de Casteljau's contributions:

Publications