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a guest Aug 25th, 2019 64 Never
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  1. #Find prime factors in python
  2. from math import sqrt
  3.  
  4. def primality_testing(n):
  5.     """test if the given number is prime or not"""
  6.     if type(n) != int:
  7.         print("the given number is not a positive integer")
  8.     elif n == 1:
  9.         return False
  10.     elif n == 2:
  11.         return True
  12.     elif n == 3: #exception occurs when n == 3
  13.         return True
  14.     elif n > 2:
  15.         if int(sqrt(n)) > 2:
  16.             for i in range(2, int(sqrt(n))):
  17.                 b = n % i #Check if the modulo of n against a trial division number i is 0
  18.                 if b == 0:
  19.                     return False #if modulo is zero, then the given number is a factor, so n is not a prime number
  20.             return True #if modulo is not zero, then the given number is not a factor, so n is a prime number
  21.         elif int(sqrt(n)) == 2: #taking out the exceptional case when sqrt(n) = 2
  22.             b = n % 2 #the trial division number here is 2
  23.             if b == 0:
  24.                 return False
  25.             return True
  26.  
  27. is_prime = primality_testing(13)
  28. print(is_prime)
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