- #1
quasar_4
- 290
- 0
Hi,
I am trying to prove that I have the correct value of an integral of the form [tex] \int_0^{2 \pi} f(\cos{\theta},\sin{\theta}) d\theta [/tex]. I want to use the residue theorem, but I have one problem: all the literature I can find says that for contour integrals of this form, you can only use the residue theorem when the poles don't lie on the contour, and my poles are at z=0 and z=-1, so both lie on the contour.
I then thought I could just indent around these poles with two small contours, but I can't find any similar examples - everything I can find using Jordan's lemma or the Cauchy principle value is for an improper integral, and that's not what I've got. So... can I make indentations on my contour, compute the contributions from the poles inside, and use the residue theorem? Or will this not be valid for my type of definite integral?
I am trying to prove that I have the correct value of an integral of the form [tex] \int_0^{2 \pi} f(\cos{\theta},\sin{\theta}) d\theta [/tex]. I want to use the residue theorem, but I have one problem: all the literature I can find says that for contour integrals of this form, you can only use the residue theorem when the poles don't lie on the contour, and my poles are at z=0 and z=-1, so both lie on the contour.
I then thought I could just indent around these poles with two small contours, but I can't find any similar examples - everything I can find using Jordan's lemma or the Cauchy principle value is for an improper integral, and that's not what I've got. So... can I make indentations on my contour, compute the contributions from the poles inside, and use the residue theorem? Or will this not be valid for my type of definite integral?