Double factorial and primorial
nisse at lysator.liu.se
Tue Dec 20 08:30:13 CET 2011
bodrato at mail.dm.unipi.it writes:
> If we really want a prime_count function in GMP I can write a more clever one
I don't know how important that is. Long-term, I think gmp should at
least export some sieving functionality which us suitable as a building
block for that.
>>> counting the primes in [1,2^34] required half the time of
>>> (sieving and) multiplying all primes in [1,3*2^28].
>> So sieving is a significant part of the work for the primorial function.
> Counting primes in [1,3*2^28] is 1/60 than counting in [1,2^34], i.e.
> 1/120 of the time to compute primorial(3*2^28).
Ooops, I didn't notice that you had very different intervals in that
Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26.
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