butterfly diagram

Edward Walter Maunder plots the first sunspot "butterfly diagram".

Butterfly diagram - a diagram used to describe FFTs.

This article is about butterfly diagrams in FFT algorithms; for the sunspot diagrams of the same name, see Solar cycle.

This pattern is best visualized in the form of the so-called butterfly diagram, first constructed by the husband-wife team of E. Walter and Annie Maunder in the early twentieth century (see graph below).

The butterfly diagram show a data-flow diagram connecting the inputs x (left) to the outputs y that depend on them (right) for a "butterfly" step of a radix-2 Cooley-Tukey FFT.