How can i integrate this function

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The discussion focuses on integrating the function \[ \int_{0}^{\inf} \frac{e^{-\frac{(x-a)^2}{b}}}{x^2-c^2} dx\] using the residue theorem, particularly in relation to the Kramers-Kronig relations. Participants suggest rewriting the function as a complex variable and integrating along a specified path that includes the real axis and a semicircular contour. The necessity of looping around the real numbers b and c is emphasized, along with the importance of calculating integrals over small semicircles around these points.

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\[ \int_{0}^{\inf} \frac{e^{-\frac{(x-a)^2}{b}}}{x^2-c^2} dx\] or \[ \int_{0}^{constant} \frac{e^{-\frac{(x-a)^2}{b}}}{x^2-c^2} dx\]

maybe application Residue theorem integral ? because this problem same the kramers kronig relation?
 
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The "residue theorem" applies to functions of a complex variable. Are you planning to rewrite the function as a function of a complex variable, with path of integration the x-axis from x- R to x+ R and the semicircle $z= R \cos(\theta)+ iR \sin(\theta)4$ and then take R going to infinity?

If b and c are real numbers then you path will need to loop around b and c on the real line. Whether your loops include b and c or not you will need to calculate the integral over those small semi-circles.
 

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