Re: Integration by substitution

*To*: mathgroup at smc.vnet.net*Subject*: [mg29821] Re: Integration by substitution*From*: Ignacio Rodriguez <ignacio at sgirmn.pluri.ucm.es>*Date*: Thu, 12 Jul 2001 02:52:34 -0400 (EDT)*Organization*: UCM*References*: <9ig788$kh5$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

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