Integrate: Assumptions in double integral
- To: mathgroup at smc.vnet.net
- Subject: [mg81438] Integrate: Assumptions in double integral
- From: Gernot Pfanner <pfannerg at no-email-reply.at>
- Date: Sun, 23 Sep 2007 04:35:52 -0400 (EDT)
Hi!
Suppose that I have an integral (integration over damped wave in two
dimensions)
Integrate[Exp(-a*ta-b*tb+i*wa*ta+iwb*tb),{ta,0,tb},{tb,0,infinity}]
Why does it not matter, whether I include assumptions
(Assumptions->{a>0,b>0,wa>0,wb>0}) or not, i.e. in both cases, I get the
same result (an conditional in dependence of real and imaginary part of
the variables). In other words, it does not seem as if Mathematica 6
recognizes the conditions for a,b,wa,wb. On the other hand, if I compute
the integral in a nested scheme
Integrate[Integrate[...,{ta,0,tb},Assumptions],{tb,0,infinity}]
I get a Lorentzian function. Why is this so?
In this spirit
With thanks for your efforts
Yours Gernot