About
Matpic is a growing collection of illustrated essays about mathematics. Each one takes a single idea and draws it until the argument is visible.
What this is not
It is not a reference. There is no attempt at coverage, no index of every theorem, no obligation to have an entry for anything in particular. Wikipedia and MathWorld already do that job, they do it well, and duplicating them at lower quality would help nobody.
The unit of content here is not the concept but the picture. An essay exists because there is a figure that explains something better than a paragraph can — and if there is no such figure, there is no essay.
How the figures are made
Every illustration is generated as SVG by code written for it. None are photographs of a whiteboard, none are exported from a drawing program, and none are bitmaps. This has a few consequences worth knowing about:
- They are sharp at any size, and they cost a few kilobytes rather than a few hundred.
- They are correct by construction. A cone sliced at 22° is sliced at 22°, because the intersection is computed rather than eyeballed.
- They respond to the light and dark themes, because they reference colour roles rather than colours.
- They are parameterised. The same generator draws four rectangles under a curve or thirty, and the essay picks.
The full set of generators is listed on the figure library page.
The stochastic ones are seeded
Some figures scatter needles on a floor or drop balls through a peg board. Those use a seeded pseudo-random generator rather than the system one, so a given figure produces exactly the same picture every time. A diagram that quietly reshuffled itself would be a small lie about what is being shown.
On being wrong
Mathematical writing aimed at a general audience has a persistent temptation to smooth over the places where a statement needs a condition attached. This site tries to resist it, and to say when a picture is doing something suggestive rather than something rigorous. Corrections are welcome and will be made.