In 1960, Xenakis composed the music NEG-ALE for Peter Kassovitz’s “Vasarely”, an abstract film on the artwork of Op-Art master Victor Vasarely, documenting an exhibition of that painter’s work at the Denise Renée Gallery. Xenakis provided music in the form of a piece entitled NEG-ALE for piccolo, horn, cello and percussion, but later withdrew the work from his catalogue.
from http://www.ubu.com/film/xenakis.html
more on Vasarely here
