Ilya Zakharevich on Fri, 26 Oct 2001 12:45:31 -0400

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Re: pari-2.2.1.alpha released

On Fri, Oct 26, 2001 at 12:34:04PM +0200, Karim BELABAS wrote:
> Of course your solution uses the second model, and is much more general.
> It is also slower.

This is irrelevant as far as it is used only when other solutions do
not work.  ;-)

> > Why I cannot lift(...,'t)? ]
> Not sure I understand this.

Maybe I do not understand the documentation of lift()...

If I use

  { subst_poly(pol, from, to) = 

  subst_poly(x^3+1, x^2+1,y)

I get

  Mod((y - 1)*x + 1, x^2 + (-y + 1))

instead of (y - 1)*x + 1 which I want.  Probably I misunderstand the
intent of the second argument to lift.

I want to hint it to lift that it should get rid of Mod(*,from-t), and
not of "something else".  How to do it?


P.S.  BTW, would the subroutine above work OK if given polynomials
      including t?