As an alternative to computationally expensive N-body simulations for
gravitational clustering, the Zel'dovich approximation was studied, in the
matter era, for 3D, 2D and 1D. PLots of the density contrast were compared
against linear theory and the exact solution. The Zel'dovich approximation was
found to perform very well in the linear regime, and to give a good
approximation well into the non-linear regime.