Re: Incorrect integral in Mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg91385] Re: Incorrect integral in Mathematica
- From: "David Park" <djmpark at comcast.net>
- Date: Tue, 19 Aug 2008 07:15:56 -0400 (EDT)
- References: <g8b8t8$8pq$1@smc.vnet.net>
You might try using the Assumptions option in the Integrate expression. In
6.0.3 (and probably in 5.0) this gives:
Integrate[
Exp[-x^2/(2 w^2)] Exp[-(y - y0)^2/(2 z^2)], {x, -Infinity,
Infinity}, {y, -Infinity, Infinity},
Assumptions -> w > 0 \[And] z > 0]
2 \[Pi] w z
--
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/
"Eran Mukamel" <emukamel at stanford.edu> wrote in message
news:g8b8t8$8pq$1 at smc.vnet.net...
> Hi All,
>
> I'm getting a nonsensical answer of 0 for the following integral in
> Mathematica 5.0 (Mac OSX):
>
> Integrate[Exp[-x^2/(2w^2)]Exp[-(y - y0)^2/(2z^2)],
> {x, -Infinity, Infinity}, {y, -Infinity, Infinity}]
>
> The result should be (2 Pi w z). Any ideas why this fails?
>
> Thanks in advance, Eran
>