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Re: Working modulo 2

• To: mathgroup at smc.vnet.net
• Subject: [mg92089] Re: Working modulo 2
• From: "David Park" <djmpark at comcast.net>
• Date: Sat, 20 Sep 2008 04:55:36 -0400 (EDT)
• References: <gavt0g$g4u$1@smc.vnet.net>

expr = 7 + x + 4 y + 4 x y + 3 z + 2 x z + 4 y z + 4 x y z

expr /. x_Integer :> Mod[x, 2]
1 + x + z

Or better:

PolynomialMod[expr, 2]
1 + x + z

There are various methods to search the documentation. One convenient method 
is to evaluate ?*keyword* to obtain all the commands that contain the 
keyword. So

?*Polynomial*

gives us a list of functions that includes PolynomialMod.


-- 
David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/


"me13013" <me13013 at gmail.com> wrote in message 
news:gavt0g$g4u$1 at smc.vnet.net...
> Howdy,
>
> How does one reduce a polynomial's coefficients modulo 2?  For
> example, I have a function that sums several polynomials, and
> currently produces a result like this:
>  7 + x + 4 y + 4 x y + 3 z + 2 x z + 4 y z + 4 x y z
> I want to reduce this to
>  1 + x + z
>
> I thought I might be able to do this by somehow coercing the terms
> into a list and then doing Sum[L[[i]],{i,1,Length[L]},Modulus->2], but
> no such luck.
>
> Any ideas?
>
> Thanks,
> Bob H
>