Gamma function Definition and 128 Threads

  1. T

    Approximating Gamma Function: Numerically Calculate \(\frac{3}{2}\)

    1. Numerically approximate \Gamma(\frac{3}{2}). Is it reasonable to define these as (\frac{1}{2})!? 2. Show in the sense of question 1. that (\frac{1}{2})! = \frac{1}{2}\sqrt{\pi} at least numerically. How am i supposed to attempt this numerically? given that i do not know additional...
  2. A

    Solve this with lower incomplete gamma function

    Homework Statement \int e^{-\frac{2Zr}{a}}*r^{-1}dr Boundaries:[0,R] Homework Equations --- The Attempt at a Solution I tried to solve this with lower incomplete gamma function and got \gamma(0,\frac{2ZR}{a}) which is infinite i think. Z=81,a:Bohr radius,R=r0*A^(1/3)...
  3. B

    Gamma function to Stirling Approximation

    Homework Statement Show that the integrand of \Gamma(s+1)=\int_{0}^{\infty} t^se^{-t}dt may be written as e^{f(t)} where f(t)=s\ln{t}-t. Show that f(t) is maximum at t=t_0 and find t_0. If the integrand is sharply peaked, expand the integrand about this point (ie Taylor expansion) and...
  4. T

    How do the Veneziano amplitudes explain the strong force?

    I Heard That the gamma function explains the strong nuclear force . \Gamma \left( z \right) = \int\limits_0^\infty {t^{z - 1} } e^{ - t} dt How does it explain the Force? Thanks
  5. M

    Simplifying Gamma(xy) Expression - Help Appreciated

    what is the simplification of the following expression (in terms of gamma and\or other functions) ? \Gamma(xy) i tried the following : \Gamma(xy)=\int^{\infty}_{0} t^{xy-1} e^{-t} dt now let t^x = s => ( after some manipulation ) \Gamma(xy)=\frac{1}{x}\int^{\infty}_{0} s^{y-1}...
  6. D

    Functions that integrate to a gamma function?

    maple syntax: int(theta^y * exp(-theta*(1-alpha) ) , theta) I have a distribution that I need to integrate, and I know the result should have a gamma function in it. The only thing I have found helpful is: http://en.wikipedia.org/wiki/Gamma_function My function is kind of in that...
  7. M

    Deriving the Beta Function Integral Using Residue Theorem

    Will some one help me to prove this identity G(n)+G(1-n)= pi/ sin npi 0<n<1 B(m,n) = (m-1)! / n(n+1)...(n+m+1) ,for beta function
  8. V

    Trouble understanding the Gamma function

    The http://en.wikipedia.org/wiki/Gamma_function" is the integral \Gamma(z)=\int_{0}^{\infty}{dt\, t^{z-1}e^{-t}} . It has poles for integers of z less than 1 and is finite everywhere else. But to me it seems like it should be infinite for non integer values of z less than 0. My reasoning...
  9. M

    How to Prove Gamma and Beta Function Identities?

    Homework Statement Need to prove these 2 identities of beta function & gamma function ? Homework Equations G(n)G(1-n)= pi/sin npi B(m,n) = (m-1)! / n (n+1)...(n+m+1) The Attempt at a Solution I tired using beta function in 1st one but did not get the solution .
  10. C

    Regression Analysis for a Gamma function

    [SOLVED] Regression Analysis for a Gamma function My regression analysis program that I developed in BASICS back in the 1980's applies for half a dozen linear equations some of which are transormed into log forms. I would like to modify my program to include this Gamma function...
  11. P

    Exponential Integral & Incomplete Gamma function

    Hello, I need to compare an exponential integral -E_{-2k}(-m) -where k is a positive integer and m just a real number- to a Gamma function \frac{1}{m^{2k+1}}\Gamma(2k+1). I am using the notation from Mathworld here http://mathworld.wolfram.com/ExponentialIntegral.html...
  12. K

    Why is the gamma function so complex?

    Hi The compound summation formula v = \frac{(m + l)!(al + a + cm)}{m!(l + 1)!} listed in the "Solve v = f(x) for x" thread uses factorials and in an effort to extend it to non-integral values of "m" and "l", I stumbled across the gamma function http://en.wikipedia.org/wiki/Gamma_function" ...
  13. T

    Gamma function (complex and negative)

    Has anyone seen this representation for gamma function before? \Gamma(z) = \int_0^1\ dt\,\, t^{z-1}(e^{-t}\, -\, \sum_{n=0}^N\frac{(-t)^{n}}{n!})\,\, +\,\, \sum_{n=0}^N\frac{(-1)^{n}}{n!}\frac{1}{z+n}\,\, +\,\, \int_1^\infty dt\,\, e^{-t}\,t^{z-1} for Re(z) > -N-1 I can't figure out how...
  14. V

    Gamma function as solution to an integral

    Homework Statement Calculate \int_0^{\frac{\pi}{2}} \frac{1}{\sqrt{1+\sin^2 x}} dx expressing its solution in terms of the gamma function. It's suggested to first use the change of variable \sin x = t Homework Equations The gamma function is defined as p>0, \Gamma(p)=\int_0^\infty x^{p-1}...
  15. J

    Exploring Gamma Function: A Grade 11 Student's Perspective

    Hey , i am in grade 11 not yet studied gamma function, and not sure if it will be in the program but i have studied it a bit on my own f(x) = gamma(x) x = 1 : y = 1 x = 2 : y = 1 x = 3 : y = 2 x = 4 : y = 6 x = 5 : y = 24 x = 6 : y = 120 and i found a pattern : 1 * 1 = 1 2 * 1 = 2 3 * 2 = 6...
  16. L

    Derivative of the Gamma Function

    Hi gang, I'm having trouble with doing a derivative of the Gamma function. I know both the definition of Gamma and Polygamma, but can't see how to get from the derivative of Gamma to Psi times Gamma. Any help or hints would be great. Thanks!
  17. K

    Gamma Function Integral in Lagrange Mechanics?

    Question: A particle of mass m starting from rest at x=1 moves along the x-axis toward the origin. Its potential energy is V=\frac{1}{2}mlnx. Write the Lagrange equation and integrate it to find the time required for the particle to reach the origin. Lagrange Equation in 1-D...
  18. B

    Finding k for Gamma Function Convergence

    For what values of k would \mathop {\lim }\limits_{x \to \infty } \frac{{\Gamma \left( {kx + 1} \right)}} {{x^{kx} }} converge?
  19. L

    Gamma Function, Gamma 1/2=root pi

    Hiya, I'm having trouble finding a simple proof for gamma of 1/2 = root pi? Any suggestions
  20. R

    Gamma function for mathphys course

    The given problem is this: Solve using the gamma function \int_0^{\infty}\sqrt{x}\exp{^{-x}}{ dx}My problem is that I don't know how to use the gamma function. It doesn't make sense to me...any insight would be helpful. Thanks in advance
  21. A

    Proving the Gamma Function Integral for $\frac{1}{2}$

    I am wondering how the following statement holds true: \Gamma\left(\frac{1}{2}\right)=\int_0^{\infty}e^{-x}x^{-\frac{1}{2}}\,dx=\sqrt{\pi} I know how to show that: \int_0^{\infty}e^{-x^2}\,dx=\frac{\sqrt{\pi}}{2} But I can't seem to apply that method (converting to a double-integral) to the...
  22. C

    Image of 1/2 under gamma function

    I am trying to follow a proof of \Gamma(\frac{1}{2}) = \sqrt{\pi} but in the way i have found this equality: \int_{0}^\frac{\pi}2sin^n xdx = \int_{0}^\frac{\pi}2cos^n xdx. I have tried unsucessfully integration for parts and I don't see how can I make some substitution. Maybe you can help...
  23. M

    Can Induction Prove Gamma Function Convergence for p≥0?

    I just learned induction in another thread and I'm curious if it can be used to prove that the gamma function converges for p\geq0. I'm not sure if it can be used in this way. Is this wrong? Gamma Function is defined as: \Gamma(p+1)=\int_0^\infty e^{-x}x^p \,dx We're trying to show that this...
  24. S

    Solving Gamma Function Integral: e^(4u)*e^(-e^u)du

    Hi. I'm having some trouble solving the following gamma function: Evaluate the integral e^(4u) * e^(-e^u)du. The upper limit is inifinity and the lower limit is 0. I'm letting x = e^(u) or u = 1 in the hope to have the function looking similar to the gamma function. But I'm having no...
  25. T

    Gamma Function: Definition & Properties

    The definition of this function is Gamma(z) = integral(0, inf)(t^(z-1)e^(-t) dt) Well, I can't understand what the t stands for. The only parameter is z... Is it an arbitrary number?
  26. H

    Can Gamma Function be used to Integrate Factorials?

    By definite integral, gamma function can be defined as \Gamma(z)= \int_{0}^{\infty} t^{z-1}e^{-t} dt I've learned some properties of Gamma function but my lecturer didn't tell us the domain of Gamma function. (I'm assuming it is defined for all non-negative real numbers). I thought of...
  27. L

    Possible to evaluate the gamma function analytically?

    Does anybody know if it's possible to evaluate the gamma function analytically? I know it becomes a factorial for integers, and there's a trick involving a switch to polar coordinates for half values, but what about any other number? I have tried using a Taylor expansion and residue...
  28. I

    Proving the Gamma Function: Using Substitution and Integral Calculus

    Hello, can anyone please me here? I need to prove that int(x^a(lnx)^b.dx= (-1)^b/((1+a)^b+1)*Gamma(b+1) by making the substitution x=e^-y this is what I have done so far: x=e^-y -> y=-lnx x=0 -> y=-(-00) =+00 x=1 -> y=0 dy/dx = -1/x -> dx=-xdy =-e^-ydy then the integral...
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