Re: Assumptions in Integrate
- To: mathgroup at smc.vnet.net
- Subject: [mg20579] Re: [mg20562] Assumptions in Integrate
- From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
- Date: Sat, 30 Oct 1999 14:54:54 -0400
- Sender: owner-wri-mathgroup at wolfram.com
I also think the Assumptions mechanism in Integrate leaves a lot to be
desired. Probably the best thing one can do right now is something like:
In[45]:=
Simplify[Integrate[Cos[n x], {x, -Pi, Pi},
Assumptions -> Element[n, Integers]], Element[n, Integers]]
Out[45]=
0
--
> From: Julian Aguirre Estibalez <mtpagesj at lg.ehu.es>
> Organization: Universidad del Pais Vasco/Euskal Herriko Unibertsitatea
> Date: Sat, 30 Oct 1999 00:14:09 -0400
> To: mathgroup at smc.vnet.net
> Subject: [mg20579] [mg20562] Assumptions in Integrate
>
> Dear Math Group,
>
> I find the results of using assumptions in Integrate somewhat
> stranege. For instance,
>
> In[21]:= Integrate[Cos[n x], {x, -Pi, Pi}]
>
> Out[21]= 2 Sin[n Pi]
> -----------
> n
>
> In[22]:= Integrate[Cos[n x], {x, -Pi, Pi},
> Assumptions -> Element[n, Integers]]
>
> Out[22]=
> 2
> 2 Sin[Sqrt[n ] Pi]
> ------------------
> 2
> Sqrt[n ]
>
> In[23]:= $Version
>
> Out[23]= "4.0 for Power Macintosh (July 20, 1999)"
>
> I know I can define my own transformation rules, but one would
> think that Mathematica should do it directly.
>
> Julian Aguirre | Voice: +34 946012659
> Departamento de Matematicas | Fax: +34 944648500
> Universidad del Pais Vasco | Postal: Aptdo. 644, 48080 Bilbao, Spain
> | email: mtpagesj at lg.ehu.es
>
>