Re: Maple gfun

[Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>]

On Wed, Dec 22, 2021 at 02:21:57PM +0100, Ruud H.G. van Tol wrote:
> 
> On 2021-12-22 14:09, Bill Allombert wrote:
> > On Wed, Dec 22, 2021 at 01:48:03PM +0100, Ruud H.G. van Tol wrote:
> 
> > > Would something like Maple's gfun be useful for PARI?
> > 
> > What does gfun ? Could you give some example ?
> 
> https://dl.acm.org/doi/10.1145/178365.178368

What I need is an example with some GP input and some expected GP output.

I will give you one:

? S=sum(i=0,20,binomial(2*i,i)*T^i)+O(T^21);
? seralgdep(S,2,2)
%8 = (4*T-1)*x^2+1

So S = sqrt(1/(1-4*T)) and indeed:

? S==sqrt(1/(1-4*T))
%10 = 1

Cheers,
Bill.