Jacopo Francesco Riccati (1676–1754) was an Italian count and mathematician who did his best work not at a university but from his own country estate near Venice. A wealthy nobleman who preferred equations to court life, he turned down prestigious offers — including, it's said, an invitation from the Tsar to lead the Saint Petersburg Academy — so he could keep doing mathematics in peace.
Riccati studied a deceptively simple-looking differential equation with a squared term in
it — nonlinear, and just awkward enough to be interesting. That equation, now called
Solving it is exactly what tells an optimal controller how hard to push — it is the engine inside the Linear-Quadratic Regulator, one of the most widely used control designs in engineering. Not bad for something a count doodled in the 1720s.
Mathematics ran in the blood. Two of Riccati's sons became notable mathematicians and
physicists in their own right — Vincenzo Riccati developed hyperbolic functions, and
Giordano Riccati did early work in what we'd now call acoustics and elasticity. The
Riccatis corresponded with the biggest names of the age, including the endlessly
feuding