All Questions
Tagged with asymptotics divergent-series
7 questions
5
votes
1
answer
183
views
History of asymptotic expansion of Laplace’s method between Laplace and Erdélyi
In 1774 Laplace understood that $I≔∫\textrm{d}x \exp kf(x)$ for $k≫0$ can be estimated if one knows 2-jet of $f$ at its point of maximum (as $I₀ ≔ ∫\textrm{d}x \exp kf₀(x)$ with $f₀$ quadratic with ...
- 455
3
votes
0
answers
171
views
The divergent sum $\sum_{n=1}^\infty (-1)^n (n^2)! x^n$
Question
I'm interested in assigning a value to the divergent series $F(x)=\sum_{n=1}^\infty (-1)^n (n^2)! x^n$. I'm hoping that (1) the definition for $F(x)$ has (one-sided) derivatives of $(-1)^n (n^...
- 1,730
1
vote
0
answers
107
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Term-wise expectation of the Taylor series for $1/X$ yields asymptotic expansion for $\mathsf EX^{-1}$. What are the conditions?
Migrated from the MSE.
Let $X\sim F_X$ denote a continuous random variable. Computing the first negative moment $\mathsf EX^{-1}$ (assuming it exists) may not be tractable and thus a common tactic is ...
3
votes
1
answer
285
views
Is there an asymptotic bound between converging and diverging series? [closed]
Let us define for every $k\in\mathbb{N}$ and every large enough $x\in \mathbb{R}$,
$$
\log^{[k]}(x) =
\begin{cases}
\log^{[k-1]}(\log(x)) & k>0 \\
x & k=0
\end{cases}.
$$
It is well known, ...
- 41
2
votes
2
answers
386
views
What is the growth rate of the sum of powers of distinct primes closest to a given a integer?
Let $n$ be a positive integer, and
$$2 = p_1 < p_2 < \dots < p_m \le n$$
be the sequence of all primes less than or equal to $n$.
For each index $j$ let $p_j^{e_j}$ be the largest power of $...
- 557
6
votes
1
answer
326
views
Riemann surface from Riccati equation
I have quite a practical question motivated by physics.
Consider the Riccati equation whose solution gives a quantum-mechanical (QM) analogue of the classical momentum:
$$
(p(x))^2 + \dfrac{\hbar}{i}...
- 171
1
vote
1
answer
522
views
Testing for asymptotic series
I would like to know if there is a systematic way of writing down an asymptotic series representation of a function?
(like one can use Taylor series expansion for doing a power series).
Conversely ...
- 3,541