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Re: Integration by substitution


In my case (Mathematica 3.0) none of them are answered.

"G. A. Garrett" wrote:

> I was wondering if someone could explain to me why the first input
> below gives no answer while the second input does. It never crossed my
> mind the Mathematica wouldn't have seen the simple substitution of
> sp=s/a that produced an answer. I am running ver. 4.0 in a Windows
> environment. I am basically looking for a characteristic that I can be
> on the look out for in the future.
>
> Integrate[Sech[s/a]^2 Sech[(t - s)/a]^2, {s, -Infinity, Infinity}]
>
> Integrate[a Sech[sp]^2 Sech[(tp - sp)]^2, {sp, -Infinity, Infinity}]
>
> Gregory
> --Posted email rarely checked--

--

Ignacio Rodriguez Ramirez de Arellano
Unidad de RMN
Universidad Complutense
Paseo Juan XXIII, 1
Madrid 28040, Spain

Tel. 34-91-394-3288
Fax  34-91-394-3245
e-mail: ignacio at sgirmn.pluri.ucm.es





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