3. Non-linear problems

We now turn to nonlinear inverse problems, focusing on the identification of parameters in differential equations.

In the general situation, we're dealing with a physical phenomenon whose structure is known, but whose precise operating parameters are not. It is possible to measure the response of this system to known inputs. The system functions like a black box, and we would like to know its contents, without "opening" the box.

We saw some examples in paragraph 1