Template:Selected anniversaries/March 18
1640: Painter, mathematician, astronomer, and architect Philippe de La Hire born. La Hire will be the favorite pupil of Desargues, and develop conic sections and epicycloids based on the teaching of Desargues.
1727: Scientist and watchmaker Ferdinand Berthoud born. Berthoud will serve as Horologist-Mechanic by appointment to the King and the Navy, leaving an exceptionally broad body of work, notable for excellent sea chronometers.
1871: Mathematician and academic Augustus De Morgan dies. De Morgan formulated two laws, now De Morgan's Laws, pertaining to mathematical induction: (1) the negation of a disjunction is the conjunction of the negations; (2) the negation of a conjunction is the disjunction of the negations.
1927: Physicist, mathematician, and activist William C. Davidon born. Davidon will develop the first quasi-Newton algorithm, now known as the Davidon–Fletcher–Powell formula.
1927: Journalist, writer, literary editor, and actor George Plimpton born. Plimpton will be famous for "participatory journalism": competing in professional sporting events, playing with the New York Philharmonic Orchestra, performing a circus trapeze act, and then recording the experience from the point of view of an amateur.
1963: Mathematician Tan Lei born. Tan Lei will specialize in complex dynamics and functions of complex numbers, making contributions to the study of the Mandelbrot set and Julia set.