Is the Integral of 1/sinh^2(x/2) a Principal Value Integral?

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SUMMARY

The integral of \( \frac{1}{\sinh^2(x/2)} \) from \(-\infty\) to \(+\infty\) evaluates to \(-2 \coth(x/2)\). This integral must be considered as a principal value integral due to the behavior of the integrand at infinity. The discussion clarifies that once limits are applied, the integral is no longer a function of \(x\), emphasizing the importance of understanding definite versus indefinite integrals.

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Belgium 12
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Hi dear members,
I have a problem with the following integral:

Integral 1/sinh^2(x/2) from -inf to +inf =-2 coth(x/2)

must I consider it as a principal value integral?

Thank you
 
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If you're integrating wrt x, you can't have x in the RHS.
 
Belgium 12 said:
Integral 1/sinh^2(x/2) from -inf to +inf =-2 coth(x/2)

Just to be clear, are you trying to evaluate
##\int_{-\infty}^{\infty} \frac{1}{\sinh ^2(x/2)} \, dx##
 
once you put limits on the integral (a definite integral, not an indefinite integral), it is no longer a function of x. is it the anti-derivative you want to prove?
 

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