Édouard Gilbert on Thu, 22 Mar 2007 16:22:57 +0100

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Newbie question: lifting polynomials coefficient

 To: pariusers@list.cr.yp.to
 Subject: Newbie question: lifting polynomials coefficient
 From: Édouard Gilbert <edouard.gilbert@eleves.bretagne.enscachan.fr>
 Date: Thu, 22 Mar 2007 16:14:43 +0100
 Deliverydate: Thu, 22 Mar 2007 16:22:57 +0100
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 Sender: Édouard Gilbert <edouard.gilbert@gmail.com>
Hi everyone,
Here is a simple problem that can be easliy avoided in a very
unelegant way.
The simple question is : how to lift the t_INTMOD coefficients of a
t_POLMOD?
For example
> P = Mod(Mod(1, 2)*X + Mod(1, 2), Mod(1, 2)*X^2 + Mod(1, 2))
% (...)
> lift(P)
% Mod(1, 2)*X + Mod(1, 2)
Of course, a workaround is
> lift(P, Y)
% Mod(X + 1, X^2 + 1)
which gives the expected results. But what if I want to lift such a
polynomial in a function?
I''ve written the following:
> foo(poly, var = very_unlikly_variable) =
{
lift(poly, var)
}
That way, the user can the variable he wants by switching the second
argument i necessary, but this solution is very unelegant
and there is the risk of seeing a var = very_unlikely_variable to
appear in every function.
Is there a nicer solution to this?
Thanks for your help,
Édouard