Convergence Definition and 1000 Threads

CONvergence is an annual multi-genre fan convention. This all-volunteer, fan-run convention is primarily for enthusiasts of Science Fiction and Fantasy in all media. Their motto is "where science fiction and reality meet". It is one of the most-attended conventions of its kind in North America, with approximately 6,000 paid members. The 2019 convention was held across four days at the Hyatt Regency Minneapolis in Minneapolis, Minnesota.

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  1. G

    Convergence in probability of the sum of two random variables

    Homework Statement X, Y, (X_n)_{n>0} \text{ and } (Y_n)_{n>0} are random variables. Show that if X_n \xrightarrow{\text{P}} X and Y_n \xrightarrow{\text{P}} Y then X_n + Y_n \xrightarrow{\text{P}} X + Y Homework Equations If X_n \xrightarrow{\text{P}} X then...
  2. T

    How Can I Prove a Sequence Converges with a Specific Limit?

    Im struggling with the concept of this basic sequence question. Let x(n) be a sequence such that lim(n->00) (nx(n)) = 0 i.e. it converges to zero... How could i show that there is an N s.t. for all n≥N : -1 < nx(n) < 1 Any tips would be great.. I don't want an answer.. I want to...
  3. H

    Is the Function Uniformly Convergent on (0,1]?

    I am given f_n(x)=\frac{nx}{nx+1} defined on [0,\infty) and I have that the function converges pointwise to 0 \ \mbox{if x=0 and} 1\ \mbox{otherwise} Is the function uniform convergent on [0,1] ? No. If we take x=1/n then Limit_{n\rightarrow\infty}|\frac{1/n*n}{1+1/n*n}-1|=0.5...
  4. M

    Does the Absolute Value of this Series Converge? A Scientist's Dilemma

    Homework Statement \sum_{n=1}^{\infty}(-1)^{n+1}\frac{\sqrt{n}+1}{n+1} Homework Equations absolute convergence test The Attempt at a Solution by book says that the series converges because \sum_{n=1}^{\infty}\frac{\sqrt{n}+1}{n+1} converges but they don't show how the absolute...
  5. Z

    Uniform Convergence of Fourier Series

    Homework Statement Find the minimum number required (value of n) for the average deviation of the Fourier Series to fall below 2% Homework Equations Use the Uniform Convergence of Fourier Series. Where Sm is the partial sum of the Fourier Series. C is constant. Here C is ∏^2 So...
  6. H

    Fourier series convergence - holder continuity and differentiability

    Homework Statement Given each of the functions f below, describe the set of points at which the Fourier series converges to f. b) f(x) = abs(sqrt(x)) for x on [-pi, pi] with f(x+2pi)=f(x) Homework Equations Theorem: If f(x) is absolutely integrable, then its Fourier series converges to f...
  7. J

    Iteration, linear function. convergence and divergence

    Homework Statement I need to understand and prove the following: That if a>1 the function diverges, except for a special case x_0= b/(1-a). Then if a=-1 diverges for some cases and converges if x_0 is b/2. Again, not to clear on this. Homework Equations lim n →∞...
  8. T

    Product of two sequences of functions [uniform convergence]

    Homework Statement This is a homework question for a introductory course in analysis. given that a) the partial sums of f_n are uniformly bounded, b) g_1 \geq g_2 \geq ... \geq 0, c) g_n \rightarrow 0 uniformly, prove that \sum_{n=1}^{\infty} f_n g_n converges uniformly (the whole...
  9. A

    How to calculate the convergence point for exponential function?

    Homework Statement I need to calculate the point of divergence for this exponential function : F(x)= 5.282 * exp ( -0.01726 * x ) may you help me in finding the method to solve such problems ? Homework Equations The Attempt at a Solution
  10. S

    Fixed Point Iteration Convergence

    Homework Statement Consider the system x = \frac{1}{\sqrt{2}} * \sqrt{1+(x+y)^2} - 2/3 y = x = \frac{1}{\sqrt{2}} * \sqrt{1+(x-y)^2} - 2/3 Find a region D in the x,y-plane for which a fixed point iteration xn+1 = \frac{1}{\sqrt{2}} * \sqrt{1+(x_n + y_n)^2} - 2/3 yn+1 =...
  11. M

    Solving Color Convergence Problem - Monte's Research

    Hello, I'm pondering over this research question. Let's suppose you've got a bunch of units which can be colored black or white. They're roaming around 2d grid in random walk. Any time a unit meets with another unit, it has an option to change color. It doesn't have to though, depending...
  12. B

    Help with testing the convergence of a series

    Hi i have to show that the series 1+2r+r2+2r3+r4+2r5+... converges for r=\frac{2}{3} and diverges for r=\frac{4}{3} using the nth root test. The sequence \sqrt[n]{a_{n}}comes a bit complicated so i was wondering if I can remove the 1st term a1=1 and show that 2r+r2+2r3+r4+2r5+... converges...
  13. J

    Use the definition of convergence to prove that the lim (1/2)^n=0

    Homework Statement Use the definition of convergence to prove that lim n→∞ (1/2)^n=0 The definition of convergence says |a_n-L|<ε Homework Equations The Attempt at a Solution As I understand it: |(1/2)^n-0|<ε |(1/2)|^n<ε then I need to solve for n...
  14. M

    Two real analysis problems: proving constancy and a uniform convergence problem

    The problem statement Let f:[a,b]→\mathbb{R} be differentiable and assume that f(a)=0 and \left|f'(x)\right|\leq A\left|f(x)\right|, x\in [a,b]. Show that f(x)=0,x\in [a,b]. The attempt at a solution It was hinted at that the solution was partly as follows. Let a \leq x_0 \leq b. For all x\in...
  15. A

    Confusion regarding the dominated convergence theorem

    So a well-known theorem from Lebesgue integration is the dominated convergence theorem. It talks about a sequence f_1,f_2,\ldots of functions converging pointwise to a function f. And if |f_n(x)| \leq g(x) for an integrable function g, then we have \int f_n \to \int f. But what if we have a...
  16. S

    Proving Quadratic Convergence via Taylor Expansion

    Homework Statement The following is a modification of Newton's method: xn+1 = xn - f(xn) / g(xn) where g(xn) = (f(xn + f(xn)) - f(xn)) / f(xn) Homework Equations We are supposed to use the following method: let En = xn + p where p = root → xn = p + En Moreover, f(xn) = f(p + En) = f(p) +...
  17. B

    Determine Series Convergence Given Convergence of a Power Series

    Homework Statement I am asked to comment on the convergence/divergence of three series based on some given information about a power series: \sum_{n=0}^{\infty}c_nx^n converges at x=-4 and diverges x=6. I won't ask for help on all of the series, so here's the first one...
  18. S

    Convergence of a Cauchy sequence

    Since I don't know how to use latex I have posed my question in word file. Yours help is greatly appreciated.
  19. B

    Does Convergence of d(x_n, x) to 0 Imply x_n Approaches x?

    Homework Statement show that x_n converges to x if and only d(x_n, x) converges to 0. Homework Equations |x_n - x| < ε for all ε>0 The Attempt at a Solution well d(x_n,x) converges to 0 if d(x_n,x)<ε i just don't know how to relate that back to |x_n - x|
  20. P

    Prove Convergence of Series Using Gauss' Test

    Homework Statement I just got done proving Gauss' test, which is given in the book as: If there is an N\ge 1, an s>1, and an M>0 such that \frac{a_{n+1}}{a_n}=1 - \frac{A}{n} + \frac{f(n)}{n^s} where |f(n)|\le M for all n, then \sum a_n converges if A>1 and diverges if A \le 1. This...
  21. S

    Convergence Interval for Newton's Method

    1. The problem statement: In what region can we choose x0 and get convergence to the root x = 0 for f(x) = e-1/x^2 Homework Equations xn+1 = xn - f(xn) / f'(xn) The Attempt at a Solution The only thing I've come across is a formula that says |root - initial point| < 1/M where M =...
  22. Z

    What is the rules regarding convergence of a Fourier series?

    If you are given part of a period of a Function, what rules would you apply to draw out the full function, so that it converges as quickly as possible as a Fourier series? thanks
  23. T

    Convergence on the unit circle

    Homework Statement Determine the behavior of convergence on the unit circle, ie |z| = 1 of: Ʃ \frac{z^{n}}{n^{2}(1 - z^{n})} Homework Equations Obviously this is divergent then z is a root of unity. The question is what happens when z is not a root of unity. The Attempt at a...
  24. C

    Finding Power Series Representation for f(x) and Interval of Convergence

    Homework Statement Find the power series representation for the function f(x)=x/(x^2-3x+2) and determine the interval of convergence. Homework Equations The Attempt at a Solution First I separate into partial fractions 2/(x-2) - 1/(x-1) 2/(x-2) = sum n=0 to infinity (x/2)^n...
  25. C

    Could gravity be a convergence of waves?

    I was just watching a television program about gravity today and it got me wondering what gravity was exactly. Most analogies used to describe gravity are of a heavy ball on a bed sheet. The ball creates a depression in the sheet and objects placed on the sheet will fall in towards the ball...
  26. B

    Determining Series Convergence using the Ratio Test

    Homework Statement I'm asked to specifically use the Ratio Test (formula below) to determine whether this series converges or diverges (if it converges, the value to which it converges is not needed.) \sum_{n=1}^{\infty}\frac{n}{(e^n)^2} Homework Equations Ratio Test: If a_n is a sequence...
  27. L

    Convergence of sequence with log

    Homework Statement prove that the series summation from n=3 to infinity of (1/(n*log(n)*(log(log(n))^p)) diverges if 0<p<=1 and converges for p>1. Homework Equations The Attempt at a Solution 2^n*a(2^n)= 1/(log(2^n)*(log(log(2^n))^p)). this is similar to the summation from n=2 to...
  28. L

    Why Does (r^n) Converge to 0?

    I know this is like very basic, but my brain just somehow couldn't accept it! Homework Statement I don't understand why does the sequence (rn) converges to 0 as n -> infinity when -1<|r|<1 The Attempt at a Solution i did quite a few ways to convince myself. Firstly, we know that...
  29. L

    Convergence of series using ratio test

    Homework Statement assume summation of series An converges with all An>0. Prove summation of sqrt(An)/n converges Homework Equations The Attempt at a Solution I Tried using the ratio test which says if lim as n goes to infinity of |Bn+1/Bn|<1 then summation of Bn converges. I let Bn...
  30. Z

    What is the convergence rate of Fourier series?

    Okay, so I didn't really understand the professor when he talked about the speed of convergence of Fourier series. The question is what kind of functions converge faster than what kind of other functions using Fourier series representation. My guess from what I have absorbed is that functions...
  31. A

    Convergence Proof: |a_n| Converges to 0 if a_n Converges to 0

    Hi, Here's another question from my analsysi HW. I get that the two sequences are equal but I'm not sure how to write it out. Any help would be great. Thanks. Homework Statement Prove that a sequence {a_n} converges to 0 iff the sequence {\lvert a_n\rvert} converges to 0. Homework...
  32. A

    Convergence Proof of Sequence a_n b_n to 0

    Hi, I'm doing some homework from my analysis class. I honestly have no idea where to start. Any help would be appreciated. Homework Statement Let {a_n} be a sequence that converges to 0, and let {b_n} be a sequence. Prove that the sequence a_n b_n converges to 0. Homework Equations...
  33. P

    Analysis - Convergence of n ^ 1/n

    1. Prove that n^(1/n) converges to 1. 3. I've attempted to define {a} = n^1/n - 1 and have shown, using the binomial formula, that n=(1+a)^2>=1+[n(n-1)/2]*a^2. I think I'm on the right track but don't know how to bring this back to the original problem to prove convergence even after staring...
  34. B

    Solving a Limit to Determine the Convergence of a Series

    Homework Statement I am asked to determine whether a series converges, and if so, to provide its sum. The problem is: \sum_{n=1}^{\infty}(-3)^{n-1}4^{-n} Homework Equations - I know that if the limit of the sequence as n->inf is finite, then the series converges at that limit. - I also...
  35. M

    Proving Convergence of Real Number Sequences with Metric Equations

    Homework Statement Prove that lim_{n} p_{n}= p iff the sequence of real numbers {d{p,p_{n}}} satisfies lim_{n}d(p,p_{n})=0 Homework Equations The Attempt at a Solution I think I can get the first implication. If lim_{n} p_{n}= p, then we know that d(p,p_{n}) = d(p_{n},p) <...
  36. D

    Order of convergence of sequence

    Homework Statement I have to find the order of convergence of the following sequence b_n = \left( \frac{5}{6} \right)^{n^2} I have numerically tested that it has to be a real number between 1 and 2, but I can't find it exactly. I also have this doubt: does every sequence have an...
  37. K

    Rate of Convergence for sin(1/x^2) with Maclaurin is undefined?

    I decided to put my attempt at a solution before the question, because the "solution" is what my question is about. Homework Statement Find the rate of convergence for the following as n->infinity: lim [sin(1/n^2)] n->inf Let f(n) = sin(1/n^2) for simplicity. 2. The attempt at a...
  38. L

    Convergence of Sequence Summation and Limit Prove

    Homework Statement let (An) be a sequence in R with |summation from n=1 to infinity(An)|< infinity. Prove lim as n goes to infinity of ((A1 +2A2+...+nAn)/n) = 0 Homework Equations The Attempt at a Solution I think |summation from n=1 to infinity(An)|< infinity means the summation...
  39. K

    Convergence of a particular infinite sum

    Homework Statement Let b_n be a bounded sequence of nonnegative numbers. Let r be a number such that 0 \leq r < 1. Define s_n = b_1*r + b_2*r^2 + ... + b_n*r^n, for all natural numbers n. Prove that {s_n} converges. Homework Equations Sum of first n terms of geometric series = sum_n...
  40. J

    Fourier series convergence test

    Homework Statement A function f(x) is given as follows f(x) = 0, , -pi <= x <= pi/2 f(x) = x -pi/2 , pi/2 < x <= pi determine if it's Fourier series (given below) F(x)=\pi/16 + (1/\pi)\sum=[ (1/n^{2})(cos(n\pi) - cos(n\pi/2))cos(nx) -...
  41. J

    Fourier series convergence question

    Homework Statement f(x) = 5, -pi <= x <= 0 f(x) = 3, 0 < x <= pi f(x) is the function of interest Find the x-points where F(x) fails to converge to f(x) Homework Equations F(x) = f(x) if f is continuous at x\in(-L,L) F(x) = 0.5[ f(x-) + f(x+) ] if f is...
  42. M

    Question about metric spaces and convergence.

    Homework Statement Let \left (X,d \right) be a metric space, and let \left\{ x_n \right\} and \left\{ y_n \right\} be sequences that converge to x and y. Let \left\{ z_n \right\} be a secuence defined as z_n = d(x_n, y_n). Show that \left\{ z_n \right\} is convergent with the limit d(x,y)...
  43. N

    Complex analysis, taylor series, radius of convergence

    Homework Statement For f(z) = 1/(1+z^2) a) find the taylor series centred at the origin and the radius of convergence. b)find the laurent series for the annulus centred at the origin with inner radius given by the r.o.c. from part a), and an arbitrarily large outer radius. Homework...
  44. L

    What Are the Properties of the Sequence (Xn)?

    Homework Statement let (Xn) be a sequence in R given by X1=1 and Xn+1=1/(3+Xn) for n>=2. prove Xn converges and find the limit. Homework Equations The Attempt at a Solution well i think using the monotone convergence theorem would help but i would have to prove that the sequence...
  45. E

    OrCAD PSpice & convergence issues

    Hi any idea what is the most relevant website to find out OrCAD PSpice ebooks, application notes and tutorials and how to resolve its convergence issues in Switch Mode Power Supplies simultions. Please be precise and quick. :cool:
  46. L

    Proving the Convergence of ∑ n/2^n to 2

    I know that the following serie converges to 2 (did in excel), still I would like to know how i can prove it step by step it. ∞ ∑ n/2^n n=1 I tried (n+1)/(2^(n+1))/(n/2^n) still I'm finding 1/2, not the 2. Any thoughts?
  47. K

    Cauchy Sequence of Continuous Fns: Uniform Convergence?

    Is it true that a cauchy sequence of continuous functions defined on the whole real line converges uniformly to a continuous function? I thought this was only true for functions defined on a compact subset of the real line. Am I wrong?
  48. O

    Limit theorems and determining convergence

    Homework Statement The Attempt at a Solution I'm having some trouble getting my head around these 3 problems. Any ideas on how to approach them are welcome.
  49. G

    Calculus II - Series and Convergence

    Homework Statement Determine if the series inf Sigma n/(2n+1) n=1 converges Homework Equations The Attempt at a Solution When i did this I originally I thought I would just apply the divergence test lim n/(2n+1) =/= 0 n->inf there fore I thought by the...
  50. G

    Ultimate Test for Convergence of infinite series?

    Hi, I'm studying infinite series and am really struggling with memorizing all the tests for convergence in my book, there's like 10 of them. I don't think I'm going to be successful in memorizing all of them. I will never be asked in my course to use a specific test to determine convergence...
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