First order exponential approximations for small arguments

Most functions of interest in engineering problems can be approximated as f(χ)=Aχ^M exp {Bχ^N} for small values of the argument χ, where A, B, M and N are constants. Such a decomposition allows one to rapidly visualize the functional dependence for small arguments, and is also useful in evaluating products and quotients of functions. Applications in electromagnetics include scattering, radiation and antenna problems