# Calculation

## Rotation-invariant Laplacian for 2D grids

14 min.
The Laplacian operator $\Delta u$ is the divergence of the gradient, that is the sum of the second-order partial derivatives $\nabla^2 u$ of a multivariate function, which represents the local curvature of this function. This operator is widely used for edge-detection1, as well as in partial-differential equations (Poisson, etc.), and other problems of machine-learning minimisation. For numerical applications in orthogonal graphs, sampled only at integer coordinates (like pixels in an image), a discrete Laplacian has to be used, and several approaches are available, that will be detailed hereafter.

## Make Jupyter Notebooks easy to blog in WordPress

13 min.
I have struggled with most solutions to convert and embed Jupyter notebooks into WordPress blog posts since I use Plotly as a graphic lib, as well as many LaTeX equations and images. Finally, I had to code my way through. Here is what I did : Write the jupyter notebook Nothing that you don’t know here. If you embed pictures in the notebook though, it would be good to upload them on your WordPress media library, then use the external URL to include them (from your server) in the Markdown cells of Jupyter.

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