[Janis Alnis] wanted to build an analog computer circuit and bought some ... ordinary differential equations. So, the circuit is an analog solution to the system of differential equations.

This analog computer on a chip is useful for certain kinds of operations that CPUs are historically not efficient at, including solving differential equations. Other applications include matrix ...

the Russian scientist Vladimir Lukyanov built an analog computer known as the "Water Integrator" or "Lukyanov's Integrator." This computer was built to solve partial differential equations.