Re: Simplifying Ploynomials

• To: mathgroup at smc.vnet.net
• Subject: [mg5672] Re: Simplifying Ploynomials
• From: hanson at physics.auburn.edu (James D Hanson)
• Date: Tue, 7 Jan 1997 11:22:47 -0500
• Organization: Auburn University Physics
• Sender: owner-wri-mathgroup at wolfram.com

```In article <5ap4ni\$kv2 at dragonfly.wolfram.com>,

> Dear Math Group,
>
> The two polynomials "messy" and "clean" below are equivalentl.
>
> messy = c0 + a*c1 - b*c1 + a^2*c2 - 2*a*b*c2 + b^2*c2
>
> clean = c0 + c1(a-b) + c2(a-b)^2
>
> If I get a polynomial like the messy one, how can I get Mma
> to convert is to the clean polynimial.
>
> I don't yet have Version 3..0.
> Using Collect and Factor in version 2.2 does no good.
> Maybe FullSimplify in version 3.0 will work.
>
> Still I would like to do this without using FullSimplify,
> because it can take a very long time.
>
>              T.E.

It is not very elegant, but it works.

In[1]:=
messy = c0 + a*c1 - b*c1 + a^2*c2 - 2*a*b*c2 + b^2*c2
Out[1]=
2                  2
c0 + a c1 - b c1 + a  c2 - 2 a b c2 + b  c2
In[2]:=
clean = Expand[messy /. a -> x + b] /. x -> a - b
Out[2]=
2
c0 + (a - b) c1 + (a - b)  c2

--
James D. Hanson                          ph. (334) 844-5044
Department of Physics                    fax (334) 844-4613
206 Allison Laboratory
Auburn University, AL 36849-5311         hanson at physics.auburn.edu

```

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