Generating function Definition and 127 Threads

  1. B

    Help with generating function problem

    Hi. I'm really struggling with this generating function problem. Any help would be greatly appreciated. Question: Find the generating function for the compositions (c1,c2,c3...,ck) such that for each i, ci is an odd integer at least 2i-1. Second part of question: Use the above...
  2. H

    Finding Probability Generating Function for H0

    Homework Statement Let Y1,Y2,... be independent identically distributed random variables with P(Y1=1) = P(Y1=-1) = 1/2 and set X0 = 1, Xn=X0 + Y1 +...+ Yn for n >= 1. Define H0 = inf { n >= 0 : Xn = 0}. Find the probability generating function Φ(s) = E(sH0). Homework Equations...
  3. C

    Moment Generating Function w/ Condtional Expectation

    Homework Statement Suppose \theta ~ ~ gamma(\alpha , \lambda) where alpha is a positive integer. Conditional on \theta, X has a Poission distribution with mean \theta . Find the unconditional distribution of X by finding it's MGT. Homework Equations The Attempt at a Solution...
  4. C

    Finding the Moment Generating Function for Uniform Distribution on (0,1)

    Homework Statement Let X be uniformly distributed over the unit interval (0,1). Determine the moment generating function of X, and using this, determine all moments around the origin. Homework Equations The Attempt at a Solution I know that the MGT is M(x) = E[ext] I'm just...
  5. B

    Moment generating function and expectation

    Homework Statement Let X denote a random variable with the following probability mass function: P(j)= 2^(-j), j=1,2,3,... (a) Compute the moment generating function of X. (b) Use your answer to part (a) to compute the expectation of X. Homework Equations m.g.f of X is M (t) =...
  6. C

    Operator in exponential function and generating function

    J.J. Sakurai Modern Quantum Mechanics p. 74 It says, [A,H] = 0; H|a'> = Ea' |a'> where H is the Hamiltonian A is any observable |a'> is eigenket of A then, exp ( -iHt/h)|a'> = exp (-iEa't/h)|a'> where h is the reduced Planck's constant. I want to know WHY ? and besides, I would...
  7. O

    How do you find the Probability Generating Function?

    Homework Statement Consider a branching process with branching probabilities given by P0=1/2 and Pj=1/3^{j} for j \geq 1 Find the probability generating function: \sum^{\infty}_{n=0} p_{n}x^{n} The Attempt at a Solution Now, the answer is supposed to be G(x) = (x+3)/(2(3-x)), but I...
  8. S

    Proving convergence of a series to its generating function

    Homework Statement The problem asks to use the Lagrange form of the remainder in Taylor's Theorem to prove that the Maclaurin series generated by f(x) = xex converges to f. From the actual answer, I'm guessing it wants me to use the Remainder Estimation Theorem to accomplish this...
  9. B

    Determine the Geometric generating function

    Homework Statement Suppose RX(t) = E[(1 − tX)−1] is called the geometric generating function of X. Suppose the random variable Y has a uniform distribution on (0, 1); ie fY (y) = 1 for 0 < y < 1. Determine the geometric generating function of Y . Homework Equations The Attempt at...
  10. C

    What is the Moment Generating Function for the Distribution f(x) = 2x?

    Homework Statement Let f(x) = 2x 0<x<1 a) Determing the Moment Generating function M(t) of X b) Use the MGT to determine all moments about the origin c) Give the 3rd central moment called the skewness Homework Equations The Attempt at a Solution a) \int^1_0 e^{tx}2x dx =...
  11. B

    Is the Moment Generating Function Solution Correct?

    Homework Statement Find the mgf of 2/25*(5-y) fo 0<y<5 Homework Equations M(t) = INT e^yt f(y)dy The Attempt at a Solution = (2*(e^(5t)-5t-1))/25t Is this ok
  12. T

    Statistics(moment generating function)

    1. Let X denote the mean of a random sample of size 75 from the distribution that has the pdf f (x) =1, 0<=x<=1. Calculate P (0.45 <X< 0.55). 2. Derive the moment-generating function for the normal density. 3. Let Y n (or Y for simplicity) be b (n, p). Thus, Y / n is approximately N [p, p (1...
  13. S

    Convergence of expansion of Legendre generating function.

    The Legendre functions may be defined in terms of a generating function: g(x,t) = \frac{1}{\sqrt{1-2xt+t^2}} Of course, \frac{1}{\sqrt{1+x}} =\sum^{\infty}_{n=0} (\stackrel{-.5}{n})x^n . However, this series doesn't converge for all x. It only converges if |x| < 1. In our case, |t^2 -...
  14. M

    Exploring Bessel Function Generating Function

    Homework Statement The Bessel function generating function is e^{\frac{t}{2}(z-\frac{1}{z})} = \sum_{n=-\infty}^\infty J_n(t)z^n Show J_n(t) = \frac{1}{\pi} \int_0^\pi cos(tsin(\vartheta)-n\vartheta)d\vartheta Homework Equations The Attempt at a Solution So far I...
  15. B

    Integral with legendre generating function

    Homework Statement Use the Legendre generating function to show that for A > 1, \int^{\pi}_{0} \frac{\left(Acos\theta + 1\right)sin\thetad\theta}{\left(A^{2}+2Acos\theta+1\right)^{1/2}} = \frac{4}{3A} Homework Equations The Legendre generating function \phi\left(-cos\theta,A\right) =...
  16. D

    How to Compute MGF of Z=XT Using Conditional Expectation?

    Homework Statement Use conditional expectation to compute the moment generating function M_z(s) of the random variable Z=XT. Homework Equations X ~ R(0,10) T ~ exp(0.1) The Attempt at a Solution By definition: M_z(s) = E(exp(sZ)) =E(exp(sXT)) The only thing I can think...
  17. M

    Finding a generating function (analyticl mechanics)

    Hi, I don't understand, in general, how am I supposed to find an appropriate generating function to a given canonical transformation. It seems to me like a lot of guesswork. Can anyone give me some guidelines? thanks.
  18. S

    Solve Generating Function to Find Linear Recurrence Relation

    Homework Statement Find a linear homogeneous recurrence relation satisfied by an=2^n+n! Homework Equations The Attempt at a Solution The teacher gave us a hint using generating functions. The generating function for f(x) is f(x)=1+2x+4x^2+8x^3+...+1+x+2x^2+6x^3+24x^4+... The...
  19. G

    Moment Generating Function problem

    I'm given the probability density function: f(x) = 3x^2 for x in [0, 1] f(x) = 0 elsewhere I want to find E[X^2] which is easy if I use the integral definition (I got 3/5). Yet, when I try and do this using Moment Generating Function (mgf) I cannot seem to get the same answer (in...
  20. J

    Generating function expectation

    A probability distribution,f(x) ,can be represented as a generating function,G(n) , as \sum_{x} f(x) n^x . The expectation of f(x) can be got from G'(1) . A bivariate generating function, G(m,n) of the joint distribution f(x,y) can be represented as \sum_{x} \sum_{y} f(x,y) n^x m^y ...
  21. A

    How to prove Chepyshev's polynomials generating function identity?

    (1-xt)/(1-2xt+t^2)=sum(Tn(x)t^n) How can i prove this equation? Could you give me a hint or suggestion?
  22. M

    How to find pdf given moment generating function

    Given that the moment generating function of a random variable is (e^t)/(2-e^t) is there a way I can go backwards and find the pdf, or could 2 different pdf's have the same mgf?
  23. G

    Finding distribution by using mgf(moment generating function)

    i have X_1,X_2,...X_n independant poisson-distributed variables with parameters: alfa_i and i=1,...k(unsure about this. however says so in the excercise) i am supposed to find the distribution of Y= SUM(from 1 to n) a_i*X_i where a_i>0 maybe one could use the "poisson paradigm" by...
  24. K

    Generating function for terms of Euler triangle?

    I'm sure this is relatively easy, but after an hour or so googling, I can't seem to find the formula for generating terms of the http://steiner.math.nthu.edu.tw/chuan/123/test/euler.htm Is this known by some other name? Maybe that's why I can't find it? Thanks
  25. S

    How do you find moment generating function?

    I have absolutly no idea how to do this. so let X be a random variable with pdf fx(xy) = x for 0<=x<=1 2 - x for 1 <= 1 <= 2 0 otherwise. I"m looking through my book, and it doesn't give examples that resembles this. all I see is the moment is e^(tk) * the function... and tI...
  26. E

    Invert Series to Find an - MathWorld

    Let be a series Sum(0,infinite)anX^n=f(x) then could it be inverted to get the an?..in fact if we set x=1/Z the series becomes anZ^-n=Zeta transform of an so we could invert this (as seen in mathworld.com),could it be done to get the an?..thanks.
  27. P

    Weird Generating Function prove

    Q: show that (1-4x)^(-1/2) generates the sequence 2n chooses n, n is defined as natural All the formulas I have requires integer exponent. I am not sure how to deal with (-1/2). Thanks for any input!
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