Re: use of prodeulerrat in a script

[Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>]

Dear Alessandro,

* Alessandro Languasco [2022-02-11 17:17]:
> I am experimenting with prodeulerrat and I am trying to generate
> (randomly ) a rational function g(x)= a(x)/b(x) and then compute
> 
> prodeulerrat(g(1/p))
> 
> g is such that deg(b)>deg(a)+2, so the product converges.
> 
> Now, I’d like to do that in a script; so 
> 
> - in input I have a parameter y (an integer),
> - I generate first g(x,y) as a polynomial in x
> - then I would like to compute prodeulerrat(g(1/p,y))
> 
> If I do so in the shell, it works nicely. 
> But I would like to write a script that do so and I am stuck on this
> because I do not know how to “pass” the information about 
> perform the infinite product on p.
> 
> What am I missing here ?
> Do you have any suggestion ? 

Can you give a concrete minimal example ? What's wrong with, e.g.,

  g = 1 - y * x^2
  prodeulerrat(substvec(g, [x,y], [1/x, 2]))

Or directly (if g is indeed a polynomial in x and y is no longer there)

  g = 1 - x^2
  prodeulerrat(subst(g, x, 1/x))

?

Cheers,

    K.B.
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite de Bordeaux         Fax: (+33) (0)5 40 00 21 23
351, cours de la Liberation    http://www.math.u-bordeaux.fr/~kbelabas/
F-33405 Talence (France)       http://pari.math.u-bordeaux.fr/  [PARI/GP]
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