Re: help with integration
- To: mathgroup at smc.vnet.net
- Subject: [mg121659] Re: help with integration
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Sat, 24 Sep 2011 22:33:29 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
On 9/23/11 at 3:43 AM, dsalman96 at yahoo.com (Salman Durrani) wrote:
>I am trying to do the following integration:
>Integrate[r^2*ArcCos[x/r] - x*Sqrt[r^2 - x^2], {x, Sqrt[3] y,
>Sqrt[r^2 - y^2]} ]
>When I try, Mathematica comes back to be with a very long
>conditional expression.
>How do I tell mathematica that r is positive, real in the above
>equation not complex.
Use Assuming to specify your assumptions. Doing
Assuming[r>0, Integrate[...]]
is sufficient to specify r is real and positive. However, to
eliminate the conditional expression for this particular
integral you will need
Assuming[r>2Y&&y>0,Integrate[...]]