German mathematician who gave the first set of conditions sufficient to guarantee the convergence of a Fourier series under the so-called Dirichlet conditions. He also studied analysis and differential equations, giving his name to the Dirichlet boundary conditions. He produced Dirichlet's theorem on primes, gave the first proof of Bertrand's postulate, and investigated Dirichlet series. He is said to have slept with Gauss's Disquisitiones Arithmeticae under his pillow. In any case, he fleshed out many of the concise and rigid proofs.

Additional biographies: MacTutor (St. Andrews)