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Strange behaviour of FiniteFields?

• To: mathgroup at smc.vnet.net
• Subject: [mg25287] Strange behaviour of FiniteFields?
• From: Wil Kortsmit <rcwil at win.tue.nl>
• Date: Tue, 19 Sep 2000 03:45:11 -0400 (EDT)
• Organization: Technische Universiteit Eindhoven
• Sender: owner-wri-mathgroup at wolfram.com

Hello,

Working with the FiniteFields package we have met some strange behaviour
when we tried to compute the product of 2 polynomials a and b with
coefficients in the field f32:

<<Algebra`FiniteFields`
f32=GF[2,{1,0,1,0,0,1}];

The 2 polynomials a and b

a[x]=x^2f32[{0,0,1,1,1}]+x*f32[{1,0,0,0,0}]+f32[{1,0,1,1,1,1}];
b[x]=x^5f32[{0,1,1,1,1}]+x^4f32[{0,0,0,1,1}]+x^3f32[{0,0,1,1,0}]+
     x^2f32[{1,0,0,0}]+x*f32[{0,1,0,1,1}]+f32[{1,0,0,0,0}];

We needed to abort the following computation because we ran out of
patience:
    
Collect[a[x]b[x],x]

Preventing the early intervention of the FiniteFields package:

Collect[a[x]b[x]/.GF->GF$,x]/.GF$->GF

gave us the result that we expected immediately.
Looking in the Mathgroup archives we didn't find a clue.
Is this a bug in the FiniteFields package or are are we doing something
wrong?
Thanks for any help.

Wil Kortsmit

• Follow-Ups:
  • Re: Strange behaviour of FiniteFields?
    • From: Daniel Lichtblau <danl@wolfram.com>