Peter Gustav Lejeune Dirichlet

Johann Peter Gustav Lejeune Dirichlet was a German mathematician. In number theory, he proved special cases of Fermat's last theorem and created analytic number theory. In analysis, he advanced the theory of Fourier series and was one of the first to give the modern formal definition of a function. In mathematical physics, he studied potential theory, boundary-value problems, and heat diffusion, and hydrodynamics.

13 February 1805

Born on the same birth day (13 February): Akio Sato (wrestler) • Aníbal Acevedo Vilá • Aung Khin • Chuck Yeager • Derek Riggs • Eliaquim Mangala • Joyce DiDonato • Luisão • Luke Voit • Marc Emery • Mats Sundin • Mena Suvari • Randy Moss • Susan Oliver • Vitinha (footballer, born February 2000) • William V, Landgrave of Hesse-Kassel • Étienne François Geoffroy

Born in the same month (February 1805): Jean Baptiste Charbonneau • Johan Jakob Nervander • Sarah Fuller Flower Adams