Henri . Cohen on Fri, 16 Mar 2018 17:57:16 +0100


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Re: Integration Methods in PARI


Quoting kevin lucas <lucaskevin296@gmail.com>:

I have been trying to evaluate the following integral in PARI:

intnum(x=0, +oo, x*exp(cos(x))*sin(sin(x))/(x^2-1))

As Bill says, the error is due to the fact that your integral diverges at
x=1. But even once this is repaired, Pari is unable to integrate an
oscillating function of this type; in fact I would be surprised if
any software could do it. And Bill's suggestion of finding the Fourier
expansion will very probably not work.