Feeding the factors to Sage's factor command to check they are prime
is precisely what proof=true is all about. Testing primality in a
proven way, for numbers bigger than 10^16 is still very slow as there
is no really good algorithm known for it. I have some code written by
a student of mine (Peter Shrimpton) in C to push this bound much
higher. But it needs some serious optimisation and to be run on a
large cluster. If anyone is interested, I can make it available, as it
is GPL'd.

In the case I reported, there is no issue with proof=true, as the
numbers involved were well below Pari's cutoff. It's simply a red
herring to be thinking about proving primality of the factors.

I believe it is well understood why the Sage factor command is so much
slower.

Bill.

On 9 Apr, 22:14, mabshoff <mabsh...@googlemail.com> wrote:
> On Apr 9, 2:11 pm, mabshoff <mabsh...@googlemail.com> wrote:
>
> > On Apr 9, 2:03 pm, Peter Jeremy <peterjer...@optushome.com.au> wrote:
>
> <SNIP>
>
> > The primality test for pari is known to be lead to false results up to
> > 10^14 or so (FLINT's is up to 10^16 IIRC what Bill told me a couple
> > days ago).
>
> Opps, I don't know what I was thinking, but the above makes no sense
> as written: What I wanted to write was that pari's probabilistic
> primality test is known to be correct for up to some bound around
> 10^14. Sorry for the double post.
>
> Cheers,
>
> Michael
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