About

Firsthand Math shows mathematics in figures you can move. Each exploration takes one idea and puts it in your hands: drag a point, turn a dial, play the figure, and watch what the mathematics does.

What you will find here

Two kinds of exploration. Digestions are long: a recent result taken apart, step by step, with figures for the steps that are hard to see. Notes are short: one idea I like, and a figure to try it with.

The topics start from my own field, networks, spectral graph theory and embeddings of metric spaces, and go out from there to results I think are worth seeing. The classics that have been done many times are not here.

Who writes it

I am Leo Torres, a mathematician. I write every page and make every figure. Where a page digests someone else's result, it says whose, and cites it.

How the pages are made

The figures are made with mathterpiece, a language for interactive mathematical figures. If you want to make your own, start there. The pages are written in RSM.

The source of every page and every figure is public, on GitHub. Text and figures are under the CC BY-NC 4.0 licence: you may reuse them, with credit, for anything that is not commercial.

Videos

Most explorations also appear as a short video on YouTube, where the figure plays. The page puts the same figure in your hands.

Mistakes

I check what I claim, but I will get things wrong. If you find a mistake, or know a better picture for something here, tell me. Corrections are noted on the page they change.