Hi!
How is it possible that to multiple longer numbers takes less time, for
example:
12546048: 14.7s / 15.3s
13591552: 14.0s / 14.2s
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2009/11/15 William Stein
>
> On Sat, Nov 14, 2009 at 4:31 PM, gerrob wrote:
> >
> > I've uploaded a new code on google group. It is using remainder tree
> > to speedup the sieving, and now it is sieving up to about log2(n)^2.
> > It means a speedup by a factor of two for large "random" input (he
2009/9/4 Cactus
>
> Looking quickly at the code, it seems that a version with sieving has
> been written but it hasn't been tested or enabled.
>
In fact for large n values it would be faster to use more primes at sieve
using a remainder tree instead of one expensive division for each prime,
wha
Another improvement? would be: use a balanced tree, this is similar to the
already posted my binary_splitting routine, that solves it in a recursive
way to compute the product of lots of numbers, but since here we need the
whole tree (to get the remainders) we can't follow exactly this recursive
so
OK, I haven't known about that group, now I'm a member of that also.
"I'm slightly confused. Isn't the first q of this form precisely q = 2p + 1?
If so, it cannot be as large as your limit."
See, we are searching for primes of the form q=2kp+1, if p is prime then it
isn't sure that 2p+1 is also p
2009/6/20 William Stein
>
> On Sat, Jun 20, 2009 at 12:52 AM, gerrob wrote:
> >
> > Hi!
> >
> > For factorial routine today I've written a fast solution that is
> > faster for large n than gmp/mpir's currently code, if n is about 1
> > million or larger.
> >
> > For n=10^6: my code takes 1.7 sec.
2009/6/11 Jeff Gilchrist
>
> On Thu, Jun 11, 2009 at 1:00 PM, gerrob wrote:
>
> > I've uploaded a new code (wagstaff2.c) in google groups to test
> > Wagstaff numbers by Anton Vrba's conjecture. It's faster than
> > wagstaff.c from Jeff Gilchrist because I'm using bitshift+bitmask
> > instead of
> My feeling, looking through your code is that:
>
> * It really sits *on top of* the mpz layer
> * It relies on some code for single limbs that is not abstracted
> anywhere in MPIR, but should be
>
> It should:
>
> * be implemented *in* the new mpir_n layer
> * the unsigned long portion should be
>
> Do you have a canonical reference on the Strong Lehmer test. As a
> number theorist, I should have heard of it, but to my embarrassment, I
> have not! {blush}
>
> Look: http://mersennewiki.org/index.php/Pocklington%27s_Theorem
in our case f=p. It doesn't mention, but in my number theory book it
2009/4/22 Cactus
>
>
>
> On Apr 22, 5:40 pm, gerrob wrote:
> > Hi!
> >
> > I've written a much faster code than the currently used in gmp/mpir.
> > Million of bits numbers can be tested in about 1 sec, but slower by a
> > factor of 2 up to about 1000 bits numbers on my pc. Tested a lot, it
> > s
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