1. Department of Statistics, School of Mathematics , University of Leeds , Leeds , LS2 9JT , UK;2. The Bioinformatics Centre, Department of Biology , University of Copenhagen , Copenhagen , Denmark
Abstract:
Motivated by examples in protein bioinformatics, we study a mixture model of multivariate angular distributions. The distribution treated here (multivariate sine distribution) is a multivariate extension of the well-known von Mises distribution on the circle. The density of the sine distribution has an intractable normalizing constant and here we propose to replace it in the concentrated case by a simple approximation. We study the EM algorithm for this distribution and apply it to a practical example from protein bioinformatics.