Rotation-invariant Laplacian for 2D grids
NOTE : this article is a work in progress and not finished yet. ## Introduction The Laplacian operator $\Delta u$ is the divergence of the second-order partial derivative $\nabla^2 u$ of a multivariate function, which represents the local curvature of this function. This operator is widely used for edge-detection[^1], as well as in [...]