On Modified Asymptotic Series Involving Confuent Hypergeometric Functions Articles uri icon

publication date

  • January 2009

start page

  • 88

end page

  • 103


  • 35

International Standard Serial Number (ISSN)

  • 1068-9613

Electronic International Standard Serial Number (EISSN)

  • 1097-4067


  • A modification of standard Poincaré asymptotic expansions for functions defined by means of Laplace transforms is analyzed. This modification is based on an alternative power series expansion of the integrand, and the convergence properties are seen to be superior to those of the original asymptotic series. The resulting modified asymptotic expansion involves confluent hypergeometric functions U(a,c,z), which can be computed by means of continued fractions in a backward recursion scheme. Numerical examples are included, such as the incomplete gamma function Gamma(a,z) and the modified Bessel function Kv(z) for large values of z. It is observed that the same procedure can be applied to uniform asymptotic expansions when extra parameters become large as well.