German mathematician who is considered the father of modern analysis. His father enrolled him in law school, where Weierstraß majored in fencing and beer-drinking. He left without his degree, and spent 15 years teaching secondary school, during which period his mathematical work was ignored. In 1854, at age 40, he published an important paper on Abelian functions which took the mathematical community by storm and earned him a professorship. Work by Weierstrass and Riemann put the finishing touches on Abelian function theory.

His work added rigor to many problems in mathematics. He developed the definition of the limit, developed the technique of analytic continuation, and studied uniform convergence (which was also independently discovered by Cauchy, Stokes, and Seidel). Weierstrass also discovered a continuous curve which has no tangent at any point which was attacked by Kronecker. Weierstraß also worked on factorials and Abel's theorem.

Weierstrass suffered from a nervous breakdown in 1859, and was plagued by dizzy spells for the rest of his life. When traveling, he kept his unfinished papers and working notes in a large white wooden box. The box was lost while Weierstraß was on a trip in 1880 and never rediscovered. He is quoted as saying, "It is true that a mathematician who is not also something of a poet will never be a perfect mathematician."

Additional biographies: MacTutor (St. Andrews)