Examples of "clouds" and "arboresences" in Xenakis' Evryali

"Graphic densities” — that is, sketches of a graphic nature (with reference to Xenakis' work as an architect) — preceded the process of writing down the score. They varied in form and gestalt; the most outstanding of them were renderings in tree-like form, the so-called “arboresences” that were tree-like brachiated curves drawn on graph paper as the written manifestations of mathematical formulas and matrices. Mathematical theories were drawn upon for the purpose of mastering clouds (or Milky Ways) of sound.

In 1979, Xenakis produced the first example of a UPIC (Unité Polygogique Informatique de CEMAMu), a digital “composing machine” that turned the curves drawn on a light shade into sounds in real time. Interesting sounds are generated by dense notations and curves assuming complex shapes.

Two examples of "Evryali" taken from a MIDI "piano-roll" view of the music:

Download unmodified midi file of "Evryali"