       Re: help! - questions about Integration

• To: mathgroup at smc.vnet.net
• Subject: [mg28856] Re: help! - questions about Integration
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Wed, 16 May 2001 03:28:05 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <9dqdvp\$4jv@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

I expect serious typing errors in your equation

A < (x^2+y^2)/(x^2 Y^2 x^2-y^2) < B

it may be
A < (x^2+y^2)/(x^4 Y^2-y^2) < B

or
A < (x^2+y^2)/(x^2 y^2+ x^2-y^2) < B

With Mathematica 4.1 *and* the correct formula you may try

Needs["Calculus`Integration`"]

Integrate[
Exp[-(x/a)^2 - (y/b)^2]*
Boole[A < (x^2 + y^2)/(x^2 y^2+ x^2 - y^2) < B],
{x, -Infinity, Infinity},
{y, -Infinity, Infinity}]

How ever your inequality does not work.

Regards
Jens

c6wang at sciborg.uwaterloo.ca wrote:
>
> Hello! I am quite new about Mathematica, can someone help me out this
> question?
>
> I want to do an integration, as written below:
>
> Integrate[Exp[-(x/a)^2-(y/b)^2],  x and y are variables (-Infinity,
> Infinity),
> integration area is defined by
> A < (x^2+y^2)/(x^2 Y^2 x^2-y^2) < B,
>
> Where a, b, A, B are invariables.
>
> I am wondering if Mathematica can find out a way to to this. Or there is a
> function from Mathematica special for this kind of integration?
>