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arXiv 1606.03576math.CA
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Touchard多项式的渐近性:一个一致逼近

The asymptotics of the Touchard polynomials: a uniform approximation

R B Paris

摘要:

最近在\cite{P1}中已经考虑了对于大$n$和变量$z$的复值的Touchard多项式$T_n(z)$(也称为指数多项式)的渐近展开,其中$|z|$可以是有限的或允许像$O(n)$一样大。当$z=-x$为负时,发现当$n/x=1/e$为负时,存在两个贡献鞍点的合并。在这里,我们确定的扩展时,$n$和$x$满足这个条件,也是一个统一的两项近似涉及艾里函数在这个值的邻域。数值结果说明了所得到的渐近近似的精度。

英文摘要:

The asymptotic expansion of the Touchard polynomials $T_n(z)$ (also known as the exponential polynomials) for large $n$ and complex values of the variable $z$, where $|z|$ may be finite or allowed to be large like $O(n)$, has been recently considered in \cite{P1}. When $z=-x$ is negative, it is found that there is a coalesence of two contributory saddle points when $n/x=1/e$. Here we determine the expansion when $n$ and $x$ satisfy this condition and also a uniform two-term approximation involving the Airy function in the neighbourhood of this value. Numerical results are given to illustrate the accuracy of the asymptotic approximations obtained.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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