Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Contour integral - falls into all exceptions to rules!

  1. Sep 1, 2008 #1
    Hi, I wa swondeirng whether there was a method of performing a particular integral I have to do.

    It looks like a contour integral, but it seems to fall into the category of exceptions to every rule I've come across, I don't want to try and write it out on here, but it has the following properties:

    * It's a trig funtion integrate dover 2pi (so if you map it into the complex plane you end up with an integral over a unit circle)

    * It's not well defined at the origin (but it IS bounded, i.e. it doesn't blow up)

    * It has poles ON the unit circle

    * If you try to distort the contour at the poles you have the following problems:

    - The integral isn't over infinity, so the poles don't lie on what would otherwise be a straight line, they're on the circle. As a result, it's difficult the try and split up the contour into intrable parts (i.e. you'd need to intgrate the function over the arcs).

    - When you try to substitute z= R+n*exp[i*phi], then let n (the radius of the distortion around the pole) tend to zero, the entire integrand tends to zero too.

    Does anybody have any idea how to deal with such an integral?
    I feel as though I've tried absolutely everything!
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted