Bessel Definition and 276 Threads

  1. K

    Small approximation of the Derivative of the Bessel function

    Hi everyone, I have an equation that contains the derivative of the Bessel Function of the first kind. I need to evaluate Jn'(x) for small values of x (x<<1). I know that Jn(x) is (x)n/(2n*n!). What is it for the derivative?
  2. fluidistic

    Calculating the Laplace transform of a Bessel function

    Homework Statement Hi guys! I'm basically stuck at "starting" (ouch!) on the following problem: Using the integral representation of the Bessel function J_0 (x)=\frac{1}{\pi} \int _0 ^\pi \cos ( x\sin \theta ) d \theta, find its Laplace transform. Homework Equations \mathbb{L}...
  3. A

    Can Bessel Functions and Cosine be Expressed as Infinite Series?

    Homework Statement Show that \cos x=J_{0}+2\sum(-1)^{n}J_{2n} where the summation range from n=1 to +inf Homework Equations Taylor series for cosine? series expression for bessel function? The Attempt at a Solution My approach is to start from R.H.S. I would like to express all...
  4. H

    Integral over spherical Bessel function

    Is there somebody who can help me how to solve this integral \int_{0}^{+\infty} dr r^{^{n+1}} e^{-\alpha r} j_l(kr)
  5. M

    Evaluate integrals using modified Bessel function of the second kind

    Hi guys, I encountered it many times while reading some paper and textbook, most of them just quote the final result or some results from elsewhere to calculate the one in that context. So I'm not having a general idea how to do this, especially this one \int_k^\inf...
  6. D

    Proof of the Laplace transformation of the Bessel function with square argument

    Homework Statement Could anyone help me please? I would like to know the proof of the following Laplace transform pair: Homework Equations \mathcal{L}_{t \rightarrow s} \left\{ J_0 \left( a\sqrt{t^2-b^2} \right) \right\}=\frac{e^{-b\sqrt{s^2+a^2}}}{\sqrt{s^2+a^2}} The Attempt at a Solution...
  7. S

    How is the Bessel function approximated by a ln function

    Homework Statement It is stated in "Mathematical methods of Physics" by J. Mathews, 2nd ed, p274, that the Bessel function of the second kind and of order zero, i.e. Y_0(x) can be approximated by \frac{2}{\pi}\ln(x)+constant as x \to 0, but no more details are given in the same text.Homework...
  8. C

    Bessel function, what does the notation in this function mean?

    Hello, I have come across the following equation and want to know what the notation means exactly: \frac{-2 \pi \gamma}{\sigma} \frac{[ber_2(\gamma)ber'(\gamma) + bei_2(\gamma)bei'(\gamma)]}{[ber^2(\gamma) + bei_2(\gamma)]} Now, I know ber is related to bessel functions. For example, I...
  9. W

    Why is the first type bessel function called first?

    what is the difference between first- and second-type bessel functions?
  10. mccoy1

    Spherical bessel differential function.

    I was looking at the above equation here: http://mathworld.wolfram.com/SphericalBesselDifferentialEquation.html Which has the following equation: {(d ²/dx²)+(d/dx)+[x²-(n+1/2)²] }z =0. In my opinion, this equation is of the order n+1/2 but the website and books claim it's of the order of a...
  11. H

    Bessel Differential Equation Problem

    Homework Statement Use the substitution x = e^t to solve the following differential equation in terms of Bessel functions: \frac{d^{2}y}{dt^2} + (e^{2t} - \frac{1}{4})y = 0 Homework Equations The Attempt at a SolutionSo, using the Chain Rule, \frac{d^{2}y}{dt^2} = e^{2t}\frac{d^{2}y}{dx^2} =...
  12. A

    Can Bessel's equation be solved using only Frobenius method?

    can we use only frobenius method to solve bessel equation?
  13. T

    I have 3 questions which are bessel, half range expression and laplace transform

    the questions are together with this file and my solutions are also attached. hope someone can comment on my solutions. thanks a lot and i hope i won't get any warning any more.
  14. K

    Solving Complex Integration Involving Bessel, Singularities

    Well, here it is. I am at a loss as to how to approach this. I understand I can use the residue theorem for the poles at a and b, those are not the problem. I have heard that you can expand the function in a Laurent series and look at certain terms for the c term , but I don't fully understand...
  15. G

    Proving Recursion relations for Bessel Functions

    Homework Statement Solve equations 1) and 2) for J_{p+1}(x) and J_{p-1}(x). Add and subtract these two equations to get 3) and 4). Homework Equations 1) \frac{d}{dx}[x^{p}J_{p}(x)] = x^{p}J_{p-1}(x) 2) \frac{d}{dx}[x^{-p}J_{p}(x)] = -x^{-p}J_{p+1}(x) 3) J_{p-1}(x) + J_{p+1}(x) =...
  16. R

    Bessel Function / Helmholtz equation

    Homework Statement I'm interested in the solution of an equation given below. (It's not a homework/coursework question, but can be stated in a similar style, so I thought it best to post here.) Homework Equations A \nabla^2 f(x)-Bf(x)+C \exp(-2x^2/D^2)=0 where A,B,C,D are...
  17. F

    Long wire problem: Deriving an expression from the Bessel Function

    A straight wire clamped vertically at its lower end stands vertically if it is short, but bends under its own weight if it is long. It can be shown that the greatest length for vertical equilibrium is l, where kl(3/2) is the first zero of J-1/3 and k=4/3r2*√(ρg/∏Y) where r is the radius, ρ is...
  18. W

    How do we create a Bessel Function graph using x, n, and m parameters?

    I want to know that how we create a graph by using the following parameters,,,,, i.e x, n and m. For example in the figure a curve for Jo(x) is starting from the point 1 on Y-axis and then crossing at point 2.2 on X-axis. In this case n=o but what are the value of x and m for the curve...
  19. E

    Integral of spherical bessel function (first kind), first order

    Hello, I am trying to solve the following integral (limits from 0 to inf). ∫j_1(kr) dr where j_1 is the first order SPHERICAL Bessel function of the first kind, of argument (k*r). Unfortunately, I cannot find it in the tables, nor manage to solve it... Can anybody help? Thanks a lot! Any...
  20. S

    Computing Integration of Bessel Function

    I tried to compute this exact solution, but faced difficulty if the value of η approaching to ζ . Let say the value of ζ is fix at 0.5 and the collocation points for η is from 0 to 1. θ(η,ζ)=e^{-ε\frac{η}{2}} \left\{ e^{-η}+\left(1-\frac{ε^2}{4}\right)^{1/2} η \int_η^ζ...
  21. D

    Are Bessel Functions Differentiable at Boundary Conditions?

    Homework Statement I want to make sure that a solution to a differrential equation given by bessel functions of the first kind and second kind meet at a border(r=a), and it to be differenitable. So i shall determine the constants c_1 and c_2 I use notation from Schaums outlines Homework...
  22. alexmahone

    MHB Differentiating Bessel functions

    Differentiate $x^{1/2}\left[c_1J_{1/4}(x^2/2)+c_2J_{-1/4}(x^2/2)\right]$.
  23. alexmahone

    MHB Is there a proof for the Bessel function of order 1?

    Prove that $\displaystyle J_1(x)=\frac{1}{\pi}\int_0^\pi\cos(\theta-x\sin\theta)d\theta$ by showing that the right-hand side satisfies Bessel's equation of order 1 and that the derivative has the value $J_1'(0)$ when $x=0$. Explain why this constitutes a proof.
  24. alexmahone

    MHB How Can Bessel Functions Be Integrated Using Recurrence Relations?

    Find $\displaystyle\int x^2J_0(x)$ in terms of higher Bessel functions and $\displaystyle\int J_0(x)$.
  25. W

    Laplace Transform of a Bessel Equation

    Hi guys, I have this question on Laplace transforms, but am not sure how to start it. The zero order Bessel function Jo(t) satisfies the ordinary differential equation: tJ''o(t) + J'o(t) + tJo(t) = 0 Take the Laplace transform of this equation and use the properties of the transform to find...
  26. T

    Verifying the integral form of the Bessel equation by substitution

    Homework Statement The following is an integral form of the Bessel equation of order n: J_n(x) = \frac{1}{\pi}\int_0^{\pi}\ \cos(x\sin(t)-nt)\ dt Show by substitution that this satisfies the Bessel equation of order n. Homework Equations Bessel equation of order n: x^2y'' + xy' +...
  27. A

    Integral of Bessel Function of the First Kind

    Homework Statement I need to show that the definite integral (from 0 to infinity) of the Bessel function of the first kind (i.e.Jo(x)) goes to 1. Homework Equations All of the equations which I was given to do this problem are shown in the picture I have attached. However, I believe the...
  28. A

    Fourier Transform of Bessel Function of the 1st Kind

    I would be grateful if someone could help me out with the problem that I have attached. I believe I have successfully answered part (a) of the question but am completely unsure of how to approach part (b). I realize it must have to do with specific properties of the delta function but I am lost...
  29. W

    Integral resulting in Bessel function

    Homework Statement \int_{0}^{\infty} \sin \left(x\right) \sin \left(\frac{a}{x}\right) \ dx = \frac{\pi \sqrt{a}}{2} J_{1} \left( 2 \sqrt{a} \right) where J_{1} is the Bessel function of the first kind of order 1. Homework Equations The Attempt at a Solution Some calculations...
  30. V

    Can You Solve This Bessel Function Equation Analytically?

    Hi, I need to solve one problem like this: (a+b)*J_{1}[x(a+b)]-(a-b)*J_{1}[x(a-b)]=c J_{1} denotes the first order Bessel function. Do you think that it is possible to solve this function in an analytical way? Thanks, Viet.
  31. fluidistic

    What is the other solution for the Bessel differential equation of order 0?

    Homework Statement The Bessel DE of order 0 is x^2y''+xy'+x^2y=0. A solution is J_0(x)-\left ( \frac{x}{2} \right ) ^2+\frac{1}{4}\left ( \frac{x}{2} \right ) ^4+... Show that there's another solution for x\neq 0 that has the form J_0(x)\ln (|x|)+Ax^2+Bx^4+Cx^6+... and find the coefficients...
  32. I

    How to Evaluate Integrals Involving Bessel Functions and Exponential Terms?

    I am doing a research degree in optical fields and ended up with the following integral in my math model. can you suggest any method to evaluate this integral please. Thanks in advance ∫(j(x) *e^(ax^2+ibx^2) dx J --> zero order bessel function i--. complex a & b --> constants
  33. R

    What is the significance of Bessel function quotients?

    Hey guys! I'm having to complete a piece of work for which I have to consider Bessel function quotients. By that I mean: Kn'(x)/Kn(x) and In'(x)/In(x) By Kn(x) I mean a modified Bessel function of the second kind of order n and by Kn'(x) I mean the derivative of Kn(x) with respect to...
  34. Peeter

    How to arrive at Bessel function solution to 1D polynomial potential

    My quantum text, leading up to the connection formulas for WKB and the Bohr-Sommerfeld quantization condition states that for \begin{align}u'' + c x^n u = 0 \end{align} one finds that one solution is \begin{align}u &= A \sqrt{\eta k} J_{\pm m}(\eta) \\ m &= \frac{1}{{n + 2}} \\ k^2 &=...
  35. F

    Looking for fortran subroutine for I Bessel function with negative order

    Hello all, I am developing a new analytical solution for a problem in flow in porous media, and I need to write it in Fortran. This solution contains the modified Bessel function of the first kind, I_n(x). The order n is a real number, and it can be both negative and positive. The argument x...
  36. A

    Integration of the product of sine and the first Bessel function

    Homework Statement I'm supposed to prove that: \int_0^∞sin(ka)J0(kp)dk = (a2 - p2)1/2 if p < a and = 0 if p > a J0 being the first Bessel function. Homework Equations The Attempt at a Solution I've tried to inverse the order of integration and then make the integral form...
  37. S

    Engineering Applications of Bessel Functions

    hi , i want to know the engineering applications of bessel function ,, can anybody help me?
  38. M

    Integrating \int xJ_0(ax)J_0(bx)dx w/ Bessel Functions

    Homework Statement How do I integrate \int_0^1 xJ_0(ax)J_0(bx)dx where J_0 is the zeroth order Bessel function?Homework Equations See above. Also, the zeroth order Bessel equation is (xy')'+xy=0The Attempt at a Solution Surely we must use the fact that J_0 is a Bessel function, since we can't...
  39. Z

    An integral about Bessel function

    Is there somebody who knows the solution (closed form) for the integral $$\int^\infty_0\frac{J^3_1(ax)J_0(bx)}{x^2}dx$$ where $a>0,b>0$ and $J(\cdot)$ the bessel function of the first kind with integer order? Reference, or solution from computer programs all are welcome. Thanks!
  40. D

    Bessel Functions and Shifted Integral Limits: How Are They Related?

    A nth order bessel function of the first kind is defined as: Jn(B)=(1/2pi)*integral(exp(jBsin(x)-jnx))dx where the integral limits are -pi to pi I have an expression that is the exact same as above, but the limits are shifted by 90 degrees; from -pi/2 to 3pi/2 My question is how does...
  41. J

    Show integral is equal to Bessel function

    Hi guys, I'm pretty sure the following is true but I'm stuck proving it: \begin{align*} \frac{1}{2\pi}\int_{-1}^1 \left(\frac{e^{\sqrt{1-y^2}}}{\sqrt{1-y^2}}+\frac{e^{-\sqrt{1-y^2}}}{\sqrt{1-y^2}}\right) e^{iyx} dy&=\frac{1}{2\pi i}\mathop\oint\limits_{|t|=1}...
  42. M

    Proof that Bessel functions tend to zero when x approaches infinity

    I am aware that Bessel functions of any order p are zero in the limit where x approaches infinity. From the formula of Bessel functions, I can't see why this is. The formula is: J_p\left(x\right)=\sum_{n=0}^{\infty}...
  43. F

    Need help finding solution to Bessel differential equation

    Hello all, need help with the following I am deriving an analytical solution for a problem in petroleum engineering. It concerns fluid flow in porous media. Anyway, the equation is (see attachment) P is pressure, it is a function of space in x-direction, so P(x) d, THETA, and z are just...
  44. A

    Derivation of bessel generating function

    Homework Statement The bessel generating function: exp(x*(t-(1/t))/2)=sum from 0 to n(Jn(x)t^(n)) Homework Equations The Attempt at a Solution exp(x*(t-(1/t))/2)=exp((x/2)*t)exp((x/2)*(1/t)) used the McLaurin expansion of exponentials. Not sure how to bring the powers equal to that...
  45. V

    Integral of Bessel function, square root and gaussian

    Hi! Does anyone know how to solve the following integral analitically? \int^{1}_{0} dx \ e^{B x^{2}} J_{0}(i A \sqrt{1-x^{2}}), where A and B are real numbers. Thanks!
  46. J

    How Do You Solve Bessel Function Integrals?

    hello,everyone i want to know how to solve this bessel function integrals: \int_{0}^{R} J_m-1(ax)*J_m+1 (ax)*x dx where J_m-1 and J_m+1 is the Bessel function of first kind, and a is a constant. thanks.
  47. B

    Zeros of bessel functions in scilab

    Hi, I use scilab 5.2.2 Ik have a problem to find the zeros or roots of the bessel functions J0,J1... Whel I write besselj(0,3) I get the value of the bessel function Jo(3)=0,2600520. Can someone help me how to find the zeros of these bessel functions in scilab. Thank you kind...
  48. Telemachus

    Solving the Bessel Equation: Find Solutions & Justify

    Hi there. I'm working with the Bessel equation, and I have this problem. It says: a) Given the equation \frac{d^2y}{dt^2}+\frac{1}{t}\frac{dy}{dt}+4t^2y(t)=0 Use the substitution x=t^2 to find the general solution b) Find the particular solution that verifies y(0)=5 c) Does any solution...
  49. Telemachus

    Solving Bessel Equation: Indicial Equation & Frobenius Solution

    Hi there. Well, I'm stuck with this problem, which says: When p=0 the Bessel equation is: x^2y''+xy'+x^2y=0 Show that its indicial equation only has one root and find the Frobenius solution correspondingly. (Answer: y=\sum \frac{(-1)^n}{ 2^{2n}(n!)^2 }x^{2n} Well, this is what I did: At...
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