Re: eval bernpol

["Ruud H.G. van Tol" <rvtol@isolution.nl>]

On 2024-01-30 13:03, Aurel Page wrote:
> Dear Ruud,
>
> You can directly compute the evaluated Bernoulli polynomial:
>
> A285068(n) = denominator(3^n * bernpol(n,1/3));

In my 2.15.4 that doesn't work.
bernpol() returns a polynomial.


> You can also revert the polynomial instead of evaluating at a rational:
>
> A285068b(n) = denominator(subst(Polrev(Vec(bernpol(n))),'x,3));

That is indeed (50%) more effective.


And it made me find the (another 20% more effective) variant:

A285068c(n) = denominator(3^n * substpol(bernpol(n),'x,3));


> On 30/01/2024 12:50, Ruud H.G. van Tol wrote:
> > Is this a canonical and effective way to use bernpol?
> >
> > A285068(n) = my(x=1/3); denominator(3^n * eval(bernpol(n)));
> >
> > ? [ A285068(n) |n<-[0..20] ]
> > % [1, 2, 2, 1, 10, 1, 14, 1, 10, 1, 22, 1, 910, 1, 2, 1, 170, 1, 266, 
> > 1, 110]
> >
> > If not, what are alternatives?

Thanks, Ruud