Abstract:
We propose an extension of the well-known  method of Laplace which  provides the  asymptotic expansion of exponential integrals. We study  the situation where the corresponding  exponent is a  function with a countably infinite set of global maximum points.  We establish   conditions for a certain  asymptotic behaviour of  this kind of integrals. Finally, we illustrate the theoretical results with two examples.
 
Key Words: Exponential integral, asymptotic behaviour, Laplace's method, Watson's lemma.
2010 Mathematics Subject Classification: Primary:  41A60; 
Secondary:  40A05, 26A42.
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