Python/other/finding_primes.py

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'''
-The sieve of Eratosthenes is an algorithm used to find prime numbers, less than or equal to a given value.
-Illustration: https://upload.wikimedia.org/wikipedia/commons/b/b9/Sieve_of_Eratosthenes_animation.gif
'''
from __future__ import print_function
from math import sqrt
def SOE(n):
check = round(sqrt(n)) #Need not check for multiples past the square root of n
sieve = [False if i <2 else True for i in range(n+1)] #Set every index to False except for index 0 and 1
for i in range(2, check):
if(sieve[i] == True): #If i is a prime
for j in range(i+i, n+1, i): #Step through the list in increments of i(the multiples of the prime)
sieve[j] = False #Sets every multiple of i to False
for i in range(n+1):
if(sieve[i] == True):
print(i, end=" ")