1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Neumann Functions

  1. Feb 7, 2008 #1
    So for an assignment I have to write a program to find the roots of the Neumann function [tex]N_{n}(x)[/tex]. However the only Neumann function I have in my class notes is:
    Which is not overly helpful, and its the only one that was "boxed" in class.

    Any hints on how I can incorporate that into a computer program to find the roots would be great!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 7, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    What system are you using to write the program? If it's something like Mathematica you should find that the Neumann function is already defined (as a form of Bessel function).
  4. Feb 7, 2008 #3
    I've never used Mathematica, though there seems to be a lot of people mentioning it. The prof wants us to use either C/C++ or FORTRAN. I have some experience with C++ so thats what I would be using.
    Also I would be compiling it in Unix/Linux, if that helps...

    Found an equation on Wikipedia:

    [tex]Y_{\alpha} = \frac{J_{\alpha}cos(\alpha \pi) - J_{- \alpha}}{sin(\alpha \pi)}[/tex]

    This one seems more promising, but not sure how to use it to find the first five roots for [tex]N_{1}[/tex], [tex]N_{2}[/tex], and [tex]N_{3}[/tex]
  5. Feb 7, 2008 #4


    User Avatar
    Science Advisor
    Homework Helper

    You should find built in functions in the C math libraries, things like jn and yn. Setting up decent approximations for transcendental functions like this is a job for a numerical analysis type person. Just finding roots once the functions are defined isn't so hard.
  6. Feb 7, 2008 #5
    Sounds doable.. will. report back with success or failure.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook