French mathematician who was abandoned as a baby on the steps of the church of St. Jean Baptiste de Rond. When he became a famous mathematician, he spurned the overtures of his mother who wished to make him part of her family. D'Alembert was a friend of Lagrange.

d'Alembert published "d'Alembert's principle " in Traité de Dynamique (1743), which was a powerful new interpretation of Newton's third law. He also studied physical astronomy, in which he solved the precession of the equinoxes, and was the first to find and solve the wave equation. His solution is now known as d'Alembert's solution in his honor.

d'Alembert believed that logarithms satisfied , but Euler wrote him explaining that . He tried unsuccessfully to prove the fundamental theorem of algebra (still known in France as d'Alembert's theorem). He discovered the Cauchy-Riemann equations in 1752 (decades prior to Cauchy or Riemann). He also advocated the use of a limiting procedure in calculus.

With Diderot, he composed the monumental 28 volume encyclopedia Dictionaire raisonné des sciences, des arts et des métiers, of which d'Alembert wrote most of the mathematical and scientific articles.

Cauchy, Diderot, Euler, Lagrange, Newton, Riemann

Additional biographies: MacTutor (St. Andrews), Bonn