A adaptive 2D subdivision algorithm to approximate the zero-isoline of a function.
The algorithm subdivides a cell into four sub-cells if the sign at the four grid points changes. If the sampled function is continuous this implies the zero transition lies within this cell. Starting from an intitial regular rectengular grid the algorithm automatically refines the grid as needed to a given depth.
For an usage example see the provided example.nb Mathematica notebook.
The license of this code is the GPLv3. If you should publish work using this code you must give credit.