12.07.18 15:15, David Mertz пише:
On Thu, Jul 12, 2018, 7:56 AM Serhiy Storchaka
<storch...@gmail.com
<mailto:storch...@gmail.com>> wrote:
* isprime(n)
Tests if n is a prime number.
How would you test this? The Miller-Rabin Primality test? For large
numbers, iterating through candidate prime divisors is pricey.
* primes()
Returns an iterator of prime numbers: 2, 3, 5, 7, 11, 13,...
How would you implements this? Sieve of Eratosthenes is really fun to
show students as a Python generator function. But the cached primes DO
grow unboundedly as you utilize the generator. Wheel factorization as
first pass? Do you cached the first N primes so the each instance of
iterator can provide initial elements much faster? What is N?
I didn't mean any concrete implementation. Sure there are enough
efficient and simple. I sometimes need a sequence of prime numbers for
solving toy problems, and quickly write something like:
def primes(n):
return (i for i in range(2, n) if all(i % j for j in
primes(int(sqrt(i)) + 1)))
Having such feature in the stdlib would be very convenient. Any
reasonable implementation is enough efficient for my purposes.
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