Re: assumptions question
- To: mathgroup at smc.vnet.net
- Subject: [mg21912] Re: assumptions question
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Fri, 4 Feb 2000 02:54:42 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <87b0rh$o6c@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
it may help you to place the Assumptions options *behind* the
integration
range
Integrate[ Sin[k r]/(k r) * Exp[-I*(h k)^2 t /(2 m h)],
{k, 0, Infinity},
Assumptions-> {Sign[m] > 0, Sign[t h] > 0}]
Hope that helps
Jens
Peter Jay Salzman wrote:
>
> Dear all,
>
> I have an integral whose output contains things which look like:
>
> (Sign[m] - I Sign[h t])
>
> Since m is mass, h is hbar and t > 0, I placed placed a:
>
> Assumptions -> {Sign[m] > 0, Sign[t h] > 0}
>
> inside the Integrate[ ] command.
>
> Integrate[ Sin[k r]/(k r) * Exp[-I*(h k)^2 t /(2 m h)],
> Assumptions-> {Sign[m] > 0, Sign[t h] > 0},
> {k, 0, Infinity}]
>
> It seems to be ignoring me. The Sign[m]'s keep showing up. Is there a way
> to tell Mathematica that m is always positive? I *thought* this was the way of
> doing it...
>
> pete