Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options answers only not deleted user 37436

Asymptotic behavior of functions, asymptotic series and related topics

8 votes

Asymptotic expansion of $\sum\limits_{n=1}^{\infty} \frac{x^{2n+1}}{n!{\sqrt{n}} }$

Edit: I corrected a typo in the coefficient of $x^{-8}$ in the expansion of $n_{0}$ for the asymptotics of $C(x)$. …
Johannes Trost's user avatar
8 votes

Asymptotic expansion of $\sum\limits_{n=1}^{\infty} \frac{x^{2n+1}}{n!{\sqrt{n}} }$

. $$ Now exchange the summation of the asymptotics in $n$ (with, say, summation index $k$) and the summation over $n$, which I assume light heartedly to be possible. …
Johannes Trost's user avatar
6 votes
Accepted

Exponential approximation for 3F2 hypergeometric function with repeated indices

Indeed the hypergeometric series is unimodal (the terms for fixed $z$ and $d$ first grow with $k$ then decrease again). The hypergeometric series is given by $$ {}_{3}F_{2}(d,d,d;d+1,d+1;z)=\sum_{k=0} …
Johannes Trost's user avatar
5 votes
Accepted

expression for infinite series with powers of factorial in denominator

I copied this from my comments above: This sum was discussed in the book "Advanced Mathematical Methods for Scientists and Engineers" by Carl M. Bender and Steven A Orszag in section 6.7 Example 4. T …
Johannes Trost's user avatar
3 votes
Accepted

Asympotics of $\int_0^{\infty} \left[ Q(m,x)\right]^d dx$

Short: The answer for $d=3$ is $a=\frac{3}{2\sqrt{\pi}}=0.846283 \dots$. Long: The integral is splitted in two at $x = m$. $$ \int_{0}^{m} \ Q(m,x)^d \ dx + \int_{m}^{\infty} \ Q(m,x)^d \ dx $$ For …
Johannes Trost's user avatar
2 votes

Limit of a hypergeometric integral

Not a full proof, but a "closed" formula with two independent finite sums. I am sure that the proof can be made more compact, but I hadn't have the time to think about it. Very important: I assume wi …
Johannes Trost's user avatar
2 votes

Asymptotic behavior of integral with gamma functions

Too long for a comment: By using the approach of @Carlo Beenakker I was able to get an asymptotic formula for $z=\frac{1}{2} + z_{0} e^{i \phi}$ with $z_{0}\rightarrow\infty$ and $-\frac{\pi}{2}<\phi …
Johannes Trost's user avatar
2 votes
Accepted

Trying to bound the generalized hypergeometric function ${}_2F_3(x+1,x+1;1,1,1;\alpha)$ as $...

You have done much of the work for yourself. Here is the last missing step: Writing the $_2 F_3$ as integral (see, e.g., http://dlmf.nist.gov/16.5.E1): $$ _2 F_3(x+1,x+1;1,1,1;\alpha)=\Gamma(x+1)^{-2 …
Johannes Trost's user avatar
1 vote

Asymptotic value of the Shannon entropy

Laplace's Method: For large $N$ the summand as function of $n$ is maximal at $n=\frac{N}{2}$. This can be seen by the Laplace-deMoivre approximation of the binomial $$ {N \choose n}\sim 2^{N}\sqrt{\fr …
Johannes Trost's user avatar
1 vote

Asymptotic growth of recurrence relation $x_n=\min\limits_{n_1+n_2=n}(a(x_{n_1}+x_{n_2})+2n_...

For $a>2$ it has the more complicated asymptotics, $O(n a^{\ln n/\ln 2})$ (Edit: or, what is the same, $O(n^{1+\ln a/ \ln 2})$). …
Johannes Trost's user avatar
0 votes
Accepted

Estimate the scale of the power series with Poisson pdf/pmf-like terms

Actually this can be solved by standard asymtotic analysis methods (with help from Mathematica): Expand the factorial in the sum with Sterling. Then do as if $k$ is continuous and find $k=k_{0}$ wher …
Johannes Trost's user avatar