The complete Zeldovich approximation

We have developed a generalization of the Zeldovich approximation that is e xact in a wide variety of situations, including planar, spherical, and cyli ndrical symmetries. We have shown that this generalization, which we carl t he complete Zeldovich approximation (CZA), is exact to second order at an a rbitrary point within any field. For Gaussian fields, the third-order error has been obtained and shown to be very small. For statistical purposes, th e CZA leads to results exact to the third order.