> It might be a lot easier to help if you gave the rational function.
> Depending on how complicated the denominator is, you basically just have to
> compute the Taylor series of the rational function, by differentiation and
> evaluation (using Taylor's formula), i.e., kind of like this is doing, but
> over GF(p):
>
> sage: f = (x^3 + x +1)/((x^4 + x^2 + 2)*x^3*(x^3-5))
> sage: f.taylor(x, 0, 4)
> -1/(10*x^3) - 1/(10*x^2) + 1/(20*x) - 7/100 + x/200 + 17*x^2/200 -
> 103*x^3/2000 - 23*x^4/2000
Hi,
sorry for not being specific enough earlier. In my particular application
f(t) = p(t)/(1-t)^n
where p is a polynomial with integer coefficients. So I am not actually
working over GF(p) and in that case the Taylor expansion seems to give me
what I want. However as I am looking into this now, I try to come up with
something more general. I am wondering what Magma is doing (maybe just Taylor
as well?) and if we want this too, e.g. that
sage: L.<t> = LaurentSeriesRing(IntegerRing())
sage: L(f)
returns the expansion? Would that make sense? Is it feasible?
Martin
--
name: Martin Albrecht
_pgp: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99
_www: http://www.informatik.uni-bremen.de/~malb
_jab: [EMAIL PROTECTED]
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