Marcel Grossmann (Hungarian: Grossmann Marcell, April 9, 1878 – September 7, 1936) was a mathematician and a friend and classmate of Albert Einstein. Grossmann was a member of an old Swiss family from Zurich. His father managed a textile factory. He became a Professor of Mathematics at the Federal Polytechnic School in Zurich, today the ETH Zurich, specializing in descriptive geometry.
https://en.m.wikipedia.org/wiki/Marcel_Grossmann