Re: lambertw
Karim Belabas <[email protected]>
| Newsgroups | gmane.comp.mathematics.pari.devel |
|---|---|
| Message-ID | <[email protected]> |
* Ilya Zakharevich [2023-11-21 04:50]:
> gp > ?lambertw
> lambertw(y,{branch=0}): solution of the implicit equation
> x*exp(x)=y. In the p-adic case, gives a solution of x*exp(x)=y if x
> has positive valuation, of x+log(x)=log(y) otherwise.
>
> First, I would rewrite it as log(x)+x = log(y) to make the match more
> clear.
Done.
> Second, I suspect that what is meant is
>
> y has positive valuation
>
> (not “x”).
Indeed. We were further missing the condition "p odd" for this branch.
For 2-adics, the condition was v_2(y) > 1; in fact, the case v_2(y) < 1
was incorrectly implemented (raised an exception).
All fixed in master. Thanks for your report !
Cheers,
K.B.
--
Pr. Karim Belabas, U. Bordeaux, Vice-président en charge du Numérique
Institut de Mathématiques de Bordeaux UMR 5251 - (+33) 05 40 00 29 77
http://www.math.u-bordeaux.fr/~kbelabas/