Re: How to define the coefficients of a polynomial to

*To*: mathgroup at smc.vnet.net*Subject*: [mg100952] Re: [mg100925] How to define the coefficients of a polynomial to*From*: Carl Woll <carlw at wolfram.com>*Date*: Thu, 18 Jun 2009 20:46:00 -0400 (EDT)*References*: <200906180854.EAA20049@smc.vnet.net>

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]; > > ComplexExpand is the tool you need: In[910]:= ComplexExpand[ Re[a0 + a1 z + a2 z^2 + a3 z^3 + a4 z^4 + a5 z^5 + a6 z^6 + a7 z^7 + a8 z^8 + a9 z^9 + a10 z^10 /. z -> 1 + I]] Out[910]= a0 + a1 - 2 a3 - 4 a4 - 4 a5 + 8 a7 + 16 a8 + 16 a9 Carl Woll Wolfram Research

**References**:**How to define the coefficients of a polynomial to be real?***From:*BHUPALA <bhupala@gmail.com>