Repeat of 2D Laplace experiment on circle with Lagrange P2 elements.

1. Fitted mesh

Done.
Since the mesh approximates the region with line segments, the L2 error can not go better than O(h^2).

2. Unfitted mesh, linear interface approximation on boundary triangles

Done.
Again, L2 error can not decrease faster than O(h^2) because of linear boundary approximation.

3. Unfitted mesh with Monte-Carlo integration on boundaries

Done (?)


4. Unfitted mesh with linear interface approximation and Monte-Carlo integration for leftover irregular regions.



5. Unfitted mesh, Moments fitting Gaussian integration on boundary triangles