Johann Friedrich Pfaff

Johann Friedrich Pfaff (1765 to 1825) was a German mathematician who spent most of his career as a professor at Helmstedt and then at Halle. Born in Stuttgart and trained first in law at the Hohe Karlsschule, he taught himself mathematics from the works of Euler, then studied at Gottingen under Kastner and at Berlin under Bode. He held the Helmstedt chair from 1788 until the university closed in 1810, where the young Carl Friedrich Gauss attended his lectures and lived in his house, and he then moved to Halle, where he also directed the university observatory. His work covered analysis, special functions and series, and his most important contribution, published in 1815, transformed a first-order partial differential equation into a system of total differential equations. That work, the origin of what are now called Pfaffian forms, went unrecognised until Jacobi took it up in 1827.