  We propose a coefficient that measures dependence in paired samples of
functions. It has properties similar to the Pearson correlation, but differs in
significant ways: 1) it is designed to measure dependence between curves, 2) it
focuses only on extreme curves. The new coefficient is derived within the
framework of regular variation in Banach spaces. A consistent estimator is
proposed and justified by an asymptotic analysis and a simulation study. The
usefulness of the new coefficient is illustrated on financial and and climate
functional data.
