Jeroen Demeyer on Tue, 28 Sep 2004 14:16:15 +0200


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Re: storing primes found by factor.


On Mon, Sep 27, 2004 at 04:31:50PM +0200, Bill Allombert wrote:
> Hello PARI-dev,
> 
> Here a patch that add a new default, factor_add_primes 
> (turned on by default) that make factorint to automatically call
> addprimes on primes factor found larger than 2^24.  
> 
> In particular if you stop a factorisation you can get the factors
> already found using addprimes(), and they will be automatically
> reused if you restart it.
> 
> As for the code, some one more familiar with the ifac machinery should
> check that it is working properly, namely it should never addprimes()
> factors that are not (BSW pseudo-)primes. I hope the '!(hint & 8)'
> achieve that goal.

Bill,

This is certainly not a bad idea, but isn't there the risk that it will
fill up the stack after hours of computations, possibly involving a lot
of factorizations?
Maybe you should bound the memory taken by such added primes, maybe the
default factor_add_primes could be the size in bytes of all these
primes.  Shouldn't be too hard too implement, except that these primes
are perhaps stored in between the manually added primes?

Jeroen