Hello,

This is a snippet from a book:

I am trying to apply the same principle to:

Rearranging:

Then:

But from another thread, a function that satisfies both partial derivatives cannot be found.

I don't know the best way to link to a another thread but here it is anyway:

I am wondering if using the Cauchy-Riemann equations for Orthogonal Trajectories doesn't work in general or if I am missing something?