Besides being a joke, I was a dispersive PDE guy and so have a perverted idea of what the Schroedinger equation is. It’s common in that field to study a nonline

Besides being a joke, I was a dispersive PDE guy and so have a perverted idea of what the Schroedinger equation is. It’s common in that field to study a nonlinear variant. A u|u|^2 term, for instance, admits sech type solutions.