Jacobi, Karl Gustav Jacob

[yah koh bee] (1804–51) German mathematician: contributed to the theory of elliptic functions, analysis, number theory, geometry and mechanics.

Jacobi was the son of a Jewish banker, and showed wide-ranging talent from childhood. He became a lecturer at Königsberg in 1826 and in 1832 he became a professor there. He encouraged students to do original work before they had read all the previous work on a topic. As he said to one student: ‘Your father would never have married, and you wouldn’t be here now, if he had insisted on knowing all the girls in the world before marrying one’. In 1848 he made a brief but disastrous foray into politics and lost for a time the royal pension on which he, his wife and seven children lived; in 1851 he died of smallpox.

Jacobi, together with , created the theory of elliptic functions, and Jacobi also applied them to number theory and developed hyperelliptic functions. He did research on differential equations and determinants, and Jacobian determinants are now used in dynamics and quantum mechanics.