Exponentially-improved asymptotics for $q$-difference equations: _2\phi_0$ and $q{\rm P}_{\rm I}
Usually when solving differential or difference equations via series solutions one encounters divergent series in which the coefficients grow like a factorial. Surprisingly, in the $q$-world the $n$th coefficient is often of the size $q^{-\frac12 n(n-1)}$, in which $q\in(0,1)$ is fixed. Hence, the d...
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Zusammenfassung: | Usually when solving differential or difference equations via series
solutions one encounters divergent series in which the coefficients grow like a
factorial. Surprisingly, in the $q$-world the $n$th coefficient is often of the
size $q^{-\frac12 n(n-1)}$, in which $q\in(0,1)$ is fixed. Hence, the
divergence is much stronger, and one has to introduce alternative Borel and
Laplace transforms to make sense of these formal series. We will discuss
exponentially-improved asymptotics for the basic hypergeometric function
_2\phi_0$ and for solutions of the $q$-difference first Painlev\'e equation
$q{\rm P}_{\rm I}$. These are optimal truncated expansions, and re-expansions
in terms of new $q$-hyperterminant functions. The re-expansions do incorporate
the Stokes phenomena. |
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DOI: | 10.48550/arxiv.2403.02196 |