Approximate an Exponential Integral (AsymptoticIntegrate)
In this example, the asymptotic expansion for an exponential integral depending on a parameter is obtained using Laplace's method. The method relies on an analysis of the integrand in a neighborhood of its maximum.
Define a function involving an exponential kernel that has a maximum at 
.
Find the leading term in the expansion of the integral.
Compare with a numerical approximation.
Obtain a better approximation by computing an extra term in the expansion.
