Find all Prime Numbers in Range



Published: 2017-05-21 11:03:23 +0000
Categories: Python,

Language

Python

Description

Will find and identify any prime numbers between the given start and end values. Primes are identified using a factorial.

Originally written as part of a solution for my May 2016 puzzle

Similar to

Snippet

import math

def checkNumPrime(n):
        ''' Check whether n is a prime number
        '''

        # Numbers less than 4 are all prime
        if n < 4:
                return True

        # Numbers divisible by 2 or 3 aren't prime
        if n%2 == 0 or n%3 == 0:
                return False

        # Create the seeds
        di=2
        i=5

        # Work out the square root of n 
        # (no need to check anything higher)
        lim = math.floor(math.sqrt(n))

        while i < lim:
                if n%i == 0:
                        return False

                i=i+di
                di=6-di

        # If we got this far, didn't find a whole number.
        # Number is prime
        return True

def calculatePrimesForRange(s,e):
        ''' Iterate over each integer between start and end

            return list
        '''
        primes = []
        while s < e:
                if checkNumPrime(s):
                        primes.append(s)
                s = s+1

        return primes

Usage Example

print calculatePrimesForRange(1,100)
[1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]

Requires

License

BSD-3-Clause

Keywords

Primes, Numbers, Range, Factorial,

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