  We study the dynamics of the mean field model of a Bose-Einstein condensed
atom cloud in a parametrically forced trap by using analytical and numerical
techniques. The dynamics is related to a classical Mathieu oscillator in a
singular potential. It is found that there are wide resonances which can
strongly affect the dynamics even when dissipation is present. Different
geometries of the forcing are discussed, as well as the implications of our
results.
