  The properties of a rotating Bose-Einstein condensate confined in a prolate
cylindrically symmetric trap are explored both analytically and numerically. As
the rotation frequency increases, an ever greater number of vortices are
energetically favored. Though the cloud anisotropy and moment of inertia
approach those of a classical fluid at high frequencies, the observed vortex
density is consistently lower than the solid-body estimate. Furthermore, the
vortices are found to arrange themselves in highly regular triangular arrays,
with little distortion even near the condensate surface. These results are
shown to be a direct consequence of the inhomogeneous confining potential.
