  Letting $P$ be a convex polytope in $\mathbb{R}^d$ with $n>d$ vertices, we
study geometric and analytical properties of the set of generalized barycentric
coordinates relative to any point $p\in P$. We prove that such sets are
polytopes in $\mathbb{R}^n$ with at most $n-d-1$ vertices, and provide results
about continuity and differentiability for the corresponding set-valued maps.
