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Timeline for Principal value of integral

Current License: CC BY-SA 3.0

11 events
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May 15, 2013 at 11:00 vote accept Mark
May 14, 2013 at 19:37 vote accept Mark
May 15, 2013 at 11:00
May 14, 2013 at 18:15 comment added Carlo Beenakker I added several more intermediate steps; is it clear now?
May 14, 2013 at 18:10 history edited Carlo Beenakker CC BY-SA 3.0
math corrected
May 14, 2013 at 17:36 comment added Mark Could you explain the last equality in detail?
May 14, 2013 at 17:30 history edited Carlo Beenakker CC BY-SA 3.0
explanation
May 14, 2013 at 17:19 history edited Carlo Beenakker CC BY-SA 3.0
derivation
May 14, 2013 at 16:06 comment added Carlo Beenakker the integral can be done as a contour integral in the complex plane, using the definition of principal value which I gave in a comment to your question above (so as the average of a contour closed in the upper and lower half of the complex plane, once picking up the pole at $x=i\epsilon$ and once at $x=-i\epsilon$; I will try to add this calculation to my answer later today.
May 14, 2013 at 15:09 comment added Mark @Carlo Beenakker: I am grateful to you for your interest to the question and your answer. I vote it up. However, this formula gives the answer, but not the method. Also the passage to the limit as $\epsilon \downarrow 0$ should be more sound because we deal with the principal value of the specific improper integral with $\cot (x)$. As far as I understand it, that notion uses two limits by itself.
May 14, 2013 at 14:12 history edited Carlo Beenakker CC BY-SA 3.0
typo
May 14, 2013 at 14:04 history answered Carlo Beenakker CC BY-SA 3.0