  Although Galerkin discretizations have been intensively employed in the IgA
context, an efficient implementation requires special numerical quadrature
rules when constructing the system of equations. To avoid this issue,
isogeometric collocation methods have been recently introduced, giving origin
to a topic of study which is proceeding almost parallel to the Galerkin
evolution. In this paper we analyze the spectral properties of the matrices
arising from isogeometric collocation methods based on GB-splines to
approximate an elliptic PDE with variable coefficients and a generic geometry
map.
