Questions involving asymptotic analysis, including growth of functions, Big-O notation, Big-Omega and Big-Theta notations.

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28 views

Asymptotic behaviour of $\sum_{k=0}^\infty \frac{n^k}{(k!)^\nu}$

Let $\nu>0$ be fixed. I am interested in the asymptotic behaviour of the series \begin{equation*}s(n,\nu)=\sum_{k=0}^\infty \frac{n^k}{(k!)^\nu} \end{equation*} in the limit $n\rightarrow\infty$. ...
2
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55 views

Asymptotic expansion of integral (Laguerre)

Consider $$L_n = \frac{1}{2\pi i } \oint_{C'} \frac{1}{(1-t)^{\alpha+1} t^{n+1}} e^{-\frac{xt}{1-t}} dt\,\,\,\,(1)$$ where $C'$ is an anticlockwise contour around zero. Now set $\alpha = n$ and I want ...
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16 views

Strategies for approximating fourier transform of $k$-th power of the $n$-th derivative of a function

For a function $f(x)$ with Fourier transform $\hat{F}(q)$, I'm interested in understanding the relationship of the Fourier transform of a power of a derivative of $f$ to $\hat{F}(q)$. Explicitly, I ...
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39 views

Asymptotics for the Alternating Mertens Function

Are there any tight bounds, or any nontrivial ones actually, known for, with the lack of a better name, the Alternating Mertens Function: $$ S(n) = \sum_{k=1}^{n} \left((-1)^k \mu\left(k ...
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62 views

$\epsilon y''+\sqrt{x}y'+y=0$, show there is no boundary layer at $x=1$ and a boundary layer of $\epsilon^{\frac{2}{3}}$ at $x=0$?

I'm so lost. If I use quadratic formula I obtain that: $$y(x) = ae^{-2\epsilon\sqrt{x}}+be^{-2x\sqrt{x}+2\epsilon\sqrt{x}}$$ with the boundary conditions $y(0)=0$ and $y(1)=1$ but how does this lead ...
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39 views

Asymptotic of a real double serie on $\mathbb{Z}$

I am interested by a real sequence $\{a_n\}_{n\in\mathbb{Z}}$ as $\sum_{n\in\mathbb{N}}\left(\vert a_n\vert + \vert a_{-n}\vert\right)$ converges. I want to find the asymptotic behavior of this ...
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35 views

Integral of product of Hermite functions with rescaled weights.

Let $$h_{k}(x)=c_{k}(-1)^k e^{\frac{x^2}{r^2}}\frac{d^k}{dx^k}e^{-\frac{x^2}{r^2}}$$ be the standard Hermite polynomials, rescaled with a given parameter $r>0$. The normalizing constant ...
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28 views

Number of ways to visit each cell of $n\times n$ board once

A piece lies on the upper-left corner of an $n\times n$ board. Let $f(n)$ denote the number of ways to move the pieces one step horizontally/vertically at a time, so that it visits each field of the ...
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58 views

Difficulty with Asymptotic Expansion of $\int_{0}^{1}\sqrt{t}e^{ixt}dt$

In the book Advanced Mathematical Methods for Scientists and Engineers by Bender and Orszag (question 6.50) we are asked to compute the asymptotic expansion of $\int_{0}^{1}\sqrt{t}e^{ixt}dt$ fully. ...
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34 views

Find $f(n)$ in $\binom {2^n} {n^4} = (f(n)+ o(1))^n$

Task is to find $f(n)$ in the following equation: $\binom {2^n} {n^4} = (f(n)+ o(1))^n$ I've found that the problem is a bit over my head. I'm attaching my partial solution below: With use of the ...
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44 views

Prove the big theta

I need to find a $n_0$ and $k$ for Big Oh and an $n_0$ and $k$ for Big Omega, to find a big theta bound for: $5n^2 - 9n = \theta(n^2)$ Can anyone help me and show me how to find these for this ...
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73 views

Comparing asymptotic growth of logarithmic functions by reasoning

As an exercise, we're sorting functions according to their asymptotical growth. When comparing these two functions, I'm getting stuck: $n^2/(\log_2 n)^3$ versus $n \log_2 n$. Using limits I am ...
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48 views

Find an asymptotic upper bound

Use the substistution method to find an asymptotic upper bound for the relation $$T(n)=3 T\left ( \frac{n}{3}+5 \right )+\frac{n}{2}$$ Try so that the bound is as accurate as possible. Consider that ...
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55 views

Density of Pythagorean triples

We define a Pythagorean triple as a triple $<a,b,c>$ such that $a,b,c\in \mathbb N$ and $a^2+b^2=c^2$. In order to avoid duplicates, we say that a triple $<a,b,c>$ is legit iff $b>a$. ...
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32 views

Incomplete Beta function $\text{B}_x(\alpha,\beta)$ approximation for large $\alpha,\beta$?

I need good asymptotic approximations to the incomplete Beta function $\text{B}_x(\alpha,\beta)$ for large values of $\alpha,\beta$. Specifically, I need approximations valid for the following ...
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88 views

asymptotic expansion of the integral for large tau

How can I proceed to resolve this integral? $$ c_1\int_{-\infty}^{\infty}{\frac{\cos\left(x\tau\right)}{\left(1 + c_{2}\,x\right)^{\alpha}}}\, \,{\rm d}x $$ where $c_1, c_2$ are positive constants, ...
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80 views

What is the sign of the generalized Stieltjes constants $\gamma_{k}(a)$?

Recall that the Stieltjes constants $\gamma_{k}$ appear as the coefficients in the regular part of the Laurent expansion of the Riemann zeta function about $s = 1$: $$ \begin{align} \zeta(s) = ...
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60 views

Do asymptotically equivalent coefficients survive convolution at least in Θ?

This is a follow-up question to this one where I asked if asymptotic equivalence of coefficients carried over after convolution, resp. why this was not the case. Answerer Daniel Fischer proposed that ...
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166 views

Interchanging limits with the prime counting function

How does one justify that $$\lim_{s \to 1} \lim_{x \to \infty} \frac{\pi(x)}{x^s} = \lim_{x \to \infty} \lim_{s \to 1} \frac{\pi(x)}{x^s}, \quad s > 1,$$ without using the fact that the primes have ...
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24 views

asymptotic approximation for number of partitions of integer that do contain 1 nor 2

Hardy and Ramanujan provided a famous asymptotic approximation to $P(n)$ the number of partitions of an integer $n$ when $n$ gets large. I wonder if there is an asymptotic approximation to ...
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133 views

perturbation theory solution of forced Duffing's equation

Question: Find the leading order of the asymptotic expansion for large t: $\frac{d^2x}{dt}+\varepsilon\beta\frac{dx}{dt}+x+\varepsilon x^3=Fcos(\frac{1}{3}\big(1+\varepsilon\omega)t\big)$ I have ...
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42 views

Asymptotic analysis of certain multiple integration of power functions

Let $t_1,\ldots,t_m>0$, and $m\ge 4$ be an even integer. Consider the function: $$ f(a,b;\mathbf{t})=\int_0^{t_1}\ldots\int_0^{t_m} |x_1-x_m|^a |x_2-x_1|^b |x_3-x_2|^a |x_4-x_3|^b \ldots ...
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35 views

Asymptotics of the differences between successive zeta zeros

Does anyone know what the asymptotic of the differences between successive zeta zeros is? Update It appears that $\zeta(n)$ is not a bad asymptotic, when the data range is stretched: ...
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44 views

Prove that (x+1)! is not O(x!)

Discrete math question which is as follows: Prove that (x+1)! is not O(x!) using only the definition of Big-Oh notation. (Hint!: log(a * b) = (log a + log b)) I used a proof by contradiction saying ...
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214 views

Big-O Notation for remainder terms in Taylor expansion

The Big-O notation is commonly used in Taylor expansions of the form $$f(x+\epsilon)=f(x)+\epsilon f'(x)+O(\epsilon^2)$$ to say that the remainder term grows at least quadratic around $\epsilon=0$. ...
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456 views

Free lecture notes to Carl Bender's Mathematical Physics video lecture course?

I am just watching Carl Bender's Mathematical Physics video lecture course (about asymptotics and its application in physics) http://www.perimeterscholars.org/328.html which is great! Are there any ...
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79 views

How to maximize speed of rest position approach of nonlinearly damped spring oscillator?

Inspired by comments to answer for this question: Suppose we have a system which is described by the equation $$\ddot x=-x+g(\dot x),$$ with initial conditions $x(0)=1$, $\dot x(0)=0$. If ...
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43 views

Asymptotic behaviour of oscillating integral

I'm interested in the big $x$ ($x \to \infty$) behaviour for the following integral $\int_{-\infty}^{\infty} \frac{dk}{\sqrt{k^2+1}} \frac{e^{-\sqrt{k^2+1}/2}}{1-e^{-\sqrt{k^2+1}}} e^{ikx}$ After a ...
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284 views

First disagreement in PROUHET THUE MORSE exponentially big?

Let two sequences of integers be $a_1, \cdots, a_n$ and $b_1, \cdots, b_n$ such that with $a_i \in \{1, \cdots n\}$ and $b_i \in \{1, \cdots, n\}$. Let $k$ be the min integer such that $\sum_{i=1}^n ...
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60 views

find the the variable that maximizes a function

I have a function that I am trying to find for what input it maximizes. $$ f(n) = {\binom{S}{2}}^{n/S}$$ I need to find the $S$ for which this function maximizes (for infinite $n$). more generally, ...
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59 views

Asymptotics for exponential integrals

Suppose I have a situation where I want to find an asymptotic expansion as $x \to \infty$ for an integral of the form: $$ \int_{a}^{b} f(t) e^{-\phi(t) x} \mathrm{d}t$$ Let us also suppose that ...
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36 views

Asymptoticity of a definite integral

friends! I read on a book that, for $\alpha>1$, "being $g$ continuous in 0 [really $g$ is continuous in $[0,1]$, if it were useful to know] and approaching the extremes of the integral 0 for $n\to ...
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39 views

Farey Sequences and how evenly is the sequence distributed

Given any $\alpha,\beta\in (0, 1)$, $k\in Z^+, n > 1$ is this true ($\mathcal{F}_n$ denotes the $n$th Farey sequence, and $\mathcal{F_n}^{\prime} = \{q:q = a + b, a\in\mathbb{Z}, ...
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33 views

A question regarding binomial coefficient

This question arose during solving an information theory problem. Suppose $l$ is the smallest integer such that $$2^l\geq {n\choose k}$$ define $\rho=\frac{k}{n}$. How we can characterize $\rho$ as a ...
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46 views

The characterization of asymptotic dimension

Let X be a metric space. The following conditions are equivalent (a)asdimX = n (b)n is the smallest integer such that for every R > 0 there exists n + 1 families Ui i=0,1,2,...,n, and S > 0 such ...
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181 views

representing integers as linear combination of integers

Let $a,b,a',b'$ be $r-\epsilon_1$ bit positive integers. Let $c,d$ be $s+\epsilon_2$ bit positive integers. Fix a pair $c,d$ and vary $a,b$ over all $r-\epsilon_1$ bit numbers. Do we have almost ...
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31 views

Is there a 2D 3-colorstate mobile automaton that grows like $ln^{0,5}(t)$?

Define an integer function $f(t)$ for an integer $t>25$ such that $|f(f(t)) - ln(t)| < \sqrt {ln(t)}+2$. Define $L(X(t))$ as the number of nonwhite states at iteration $t$ of mobile automaton ...
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89 views

Asymptotic of Stirlings numbers of the first kind

I am trying to find some asymptotic expression for the unsigned stirling numbers of the first kind. Lets denote them by $|s(n,k)|$, and suppose that $k$ is fixed. So far I have tried using the fact ...
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80 views

Upper Bound on $\frac{1}{1-\beta u}-\sum\limits_{n=0}^{\infty}\frac{e^{-u}u^n}{n!(1-\beta(n+1))}$

Is there any procedure to find an upper bound of the following expression? $$\frac{1}{1-\beta u}-\sum_{n=0}^{\infty}\frac{e^{-u}u^n}{n!(1-\beta(n+1))}$$ Here $u,\beta\in\mathbb{R},\ u>1,\ ...
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171 views

Convergence to non-degenerate limit.

If $X_1,X_2......$ follow Poisson$(λ)$. Can we find suitable constants $a_n$ and $b_n$ such that $a_n(Y_n - b_n)$ converges to a non degenerate limit where $Y_n = (1 - \frac{1}{n})^{n\bar{X}_n}$. I ...
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59 views

Bounds on a rapidly increasing sequence

I read about a sequence similar to this one here on Stack Exchange a while back, somebody used it as an example for something that I can't recall! However, when I read about it it made me come up with ...
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109 views

Aymptotic analysis for Following fucntions

Below is an excercise from algorithm design manual For each pair of expressions (A,B) below, indicate whether A is O, o, Ω, ω, or Θ of B. Note that zero, one or more of these relations may hold for a ...
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58 views

Asymptotics and Related Properties

I have a rather general question: If there are two integer sequences such that $$\lim_{n\to\infty}A(n)/n=\lim_{n\to\infty}B(n)/n=c$$ is there anything else that can be said about them necessarily? ...
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52 views

Solving $B(n)=3B(\frac{n}{\log_{2}n}) +n$ using master theorem.

First of all sorry if this has been posted before, I found lots of master theorem questions on the search but not one like this. I am familiar with master theorem but a little uncomfortable with ...
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121 views

Weighted sum of ratio of partial sum of binomial coefficients

I would like to approximate the following sum when $n \rightarrow \infty$ and $n \gg k$, $$\sum_{x = k}^n \sum_{y > x}^n \frac{\sum_{m = 0}^{k - 1} {y - 2 \choose m}}{\sum_{m = 0}^k {y - 1 \choose ...
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0answers
69 views

Bounding an implicitly defined sequence

I have a sequence $\lambda_0,\lambda_1,\ldots,$ which is defined implicitly as $$ \lambda_0 = \frac{1}{2},$$ and $$\lambda_{k+1} = \max_{\lambda\in[1,b]} \left\{\frac{1}{2\lambda}\prod_{0\leq ...
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45 views

How prove this $\frac{|x-z|}{|x-y|}=1+\frac{1}{|x|}\hat{x}\cdot(y-z)+O(1/|x|^2)$

prove that $$\dfrac{|x-z|}{|x-y|}=1+\dfrac{1}{|x|}\hat{x}\cdot(y-z)+O(1/|x|^2)$$ for $|x|\longrightarrow \infty$ where $$\hat{x}=\dfrac{x}{|x|}$$ This problem from book,following is my idea: ...
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113 views

At large times, $\sin(\omega t)$ tends to zero?

While doing a calculation in quantum mechanics, I got a expression $\sin(\omega t)$, and my prof said if I consider the consider at large times, then i can assume that this goes to zero because at ...
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156 views

Upper bound for linear function

What may be more surprising is that when $a>0$, any linear function $an +b$ is $\mathcal{O}(n^2)$ which is easily verified by taking $c = a + |b|$ and $n_o = \max (\frac{-b}{a}, 1)$. $$an + b ...
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146 views

Big and Small O Notation

I am currently trying to learn the meaning of the Landau Symbols a bit better by solving exercices, namely the following three: $f_1(x) + f_2(x) = O(g_1(x) + g_2(x))$ given that for each f(x) the ...