Joseph Liouville (date unknown)
Joseph Liouville. Portrait of Joseph Liouville (1809-62), French mathematician. Liouville devel- oped the theory of linear differential equations. He helped to develop the Sturm-Liouville theorem which generalised Fourier's work & is important in physics. He worked on boundary-value problems, differential geometry, conformal transformation theory and complex analysis. His work influenced the development of measure theory and statistical mechanics. He proved the existence of an infinite number of transcendental numbers - those which cannot be solutions of polynomial equations with rational coefficients. He founded the influential Journal de Mathematiques in 1836.