Re: How to define the coefficients of a polynomial to be real?
- To: mathgroup at smc.vnet.net
- Subject: [mg100932] Re: How to define the coefficients of a polynomial to be real?
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Thu, 18 Jun 2009 06:18:16 -0400 (EDT)
- Organization: Uni Leipzig
- References: <h1cvbi$ji2$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
Hi,
$Assumptions = {Element[a0, Reals]}
and
Simplify[Re[a0]]
will work.
Regards
Jens
BHUPALA wrote:
> I have a 10th order polynomial (a0+a1 z+a2 z^2 + ... + an z^10). I
> want to define all the coefficients to be real. I want to substitute z
> = 1+i and extract only real part of it.
>
> I have done this by defining
>
> Element[a0,Reals];
> Element[a1,Reals];
> .
> .
> .
> Element[a10,Reals];
>
> Ply = a0+a1z+a2 z^2 + ... + an z^10;
> Ply/. z-> 1+I
>
> I am getting
>
> -2 Im[a2]+Re[a0+(1+i) a1-(2-2i)a3- 4a4]
>
> which I should not have got as I have defined already defined the
> coeffs to be real.
>
> Any help please!
>
> bhupala
>