The mathematician who drew calculus

Håkan Lennerstad is professor emeritus in mathematics at Blekinge Institute of Technology in Karlskrona, Sweden. He studied technical physics at Chalmers in the 1970s, took his PhD in 1990, and has taught at BTH since 1992, professor since 2013. He calls himself “a humanist in mathematics.”

The periodic table of mathematical functions is his own invention: a geometric formula collection, drawn by hand over many years. Every square, every property glyph and every relation arrow is his: 116 functions in 13 families, 30 properties, 7 relations.

The idea is simple and radical: functions, like elements, form families, and if you lay them out so the structure shows, a student can see calculus instead of memorising it. “This is graphical mathematics!”