Re: divisors/factor problem in 2.4.0 (development CHANGES-1.1570)

[Phil Carmody <thefatphil@yahoo.co.uk>]

--- Phil Carmody <thefatphil@yahoo.co.uk> wrote:
> In some contexts, divisors(3)=[1], and factor(3)=[;] alas.
> Not had time to check other versions or anything.
> Once you have a value that refuses to factor, it 'infects' all other values
> it touches (so factor(round(broken*210.0))=[;] too).

> ? const=poly/pdiv[length(pdiv)]
> %63 = 3

Despite what it looks like, that's not 3. It's a polynomial.

I discovered this by taking its square root, and finding out 
that I was left with a +O(x^16) term.

? sqrt(const)
1.732050807568877293527446341 + O(x^16)

So my problem can be solved simply by using polcoeff to extract the Z element
from the Z[x] object.

The general form of t_POL/t_POL is a t_RFRAC. However, Pari is prepared 
to detect the situation where the division is an exact one or not and 
to output a t_POL instead in that case. Is there any reason why it should 
not also be prepared to recognise exact integer ratios too? 

Phil





()  ASCII ribbon campaign      ()    Hopeless ribbon campaign
/\    against HTML mail        /\  against gratuitous bloodshed

[stolen with permission from Daniel B. Cristofani]

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com