(1941) Konrad Zuse he invented Z3 - the first computer designed to solve complex engineering equations rather than basic arithmetic problems.

(1942) Howard Aiken he invented Mark I - the first stored program computer.

(1942) John Atanasoff and Clifford Berry they invented eletronic computer called the ABC ( Atanasoff-Berry Computer) - It was the first computer to use electricity in the form of vacuum tubes to help make electric computation possible.
It was used for solving complex systems equations.