Re: pari-2.2.1.alpha released

[Ilya Zakharevich <ilya@math.ohio-state.edu>]

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) = 
    local(t='subst_poly_t);
    subst(lift(Mod(pol,from-t),t),t,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?

Ilya

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