[Tutor] prime factorisation

[Bernd Hewener]

Dear python tutors,

for training purposes, I am writing a Python program for prime factorisation.

Functions for reading in the number and finding the primes are working alright (of Course, finding primes up to ½ Number would suffice).

Still, the function for finding the factorization itsel does not work. I am not sure, but the number i running through the primes for checking does not seem to work properly.

Would you please be so kind as to help?

Thank you very much.

Best wishes,

Bernd


# This program calculates the prime factors of a number entered.

primefactors = []

n, num = 0, 0

def readin():
    print ("Readin")
    while True:
        num = input("Please enter a positive integer n for prime factorization. ")
        try:
            n = int(num)
            return n
        except ValueError or num < 1:
                print("Please enter a _positive_ integer!")
        else:
            break

def prime_find(l):
    #print ("Primefind " + str(l))
    primes = []
    for num in range(2, l + 1):
        for i in primes:
            if (num % i) == 0:
                break
        else:
            primes.insert(0, num)
    return primes

def prime_factorization(k):
    print ("Prime factorization")
    prime_facs = []
    for i in range(len(prime_find(k)):
        while k % i == 0:
            prime_facs.insert(0, i)
            k = k / i
        else:
            break
        return prime_facs

number = readin()
primes = prime_find(number)
print ("Prime numbers up to " + str(number) + " are:")
print (primes)
prime_factor = prime_factorization(number)
print (prime_factor)

"""def PrimFaktorZerlegung(n):
  #Primen enthält Primzahlen. Wir hoffen, dass 
  #alle Primteiler in diese List zu finden sind.
  #Sie kann ein Parameter, oder ein Klasskonstant sein
  for p in range(len(Primen)):
    while n % p == 0:
      Teiler.append(p)
       n = n/p
  return Teiler"""