  We propose a simple variational form of the wave function to describe the
ground state and vortex states of a system of weakly interacting Bose gas in an
anisotropic trap. The proposed wave function is valid for a wide range of the
particle numbers in the trap. It also works well in the case of attractive
interaction between the atoms. Further, it provides an easy and fast method to
calculate the physical quantities of interest. The results compare very well
with those obtained by purely numerical techniques. Using our wave function we
have been able to verify, for the first time, the predicted behaviour of aspect
ratio.
