>>16694571
>with self intersections and sharp extrema
What I’m going to propose is quite specialized, but algebraic geometry studies algebraic curves (among other varieties) and how locus points indicate algebraic multiplicites. It’s quite similar in spirit to how one can analyze non-essential singularities in complex analysis via contour integrals and Laurent series. Algebraic geometry has a nice connection to differential geometry via the Serre-Swan theorem. So you can likely research your analytic problem using abstract algebra.