CODEWITHSUNDEEP
python
user1460981
user1460981

Reputation: 1

Python: Recursion depth exceeded error

I reworked the program to get large prime numbers. Now it works fine, except I get a large number of red phrases at the end, after all the output is printed. Could someone please tell me why?

The end is of the output is:

(100000939.0, 'is prime')
(100000963.0, 'is prime')
(100000969.0, 'is prime')

The error is

Traceback (most recent call last):
  File "C:/Users/Marcela/Documents/Prime numbers to 100", line 48, in <module>
    loopfunction()
  File "C:/Users/Marcela/Documents/Prime numbers to 100", line 35, in loopfunction
    loopfunction()
  File "C:/Users/Marcela/Documents/Prime numbers to 100", line 35, in loopfunction
    loopfunction()
  File "C:/Users/Marcela/Documents/Prime numbers to 100", line 35, in loopfunction
    loopfunction()
...(many lines of it, the int ends with:) 
File "C:/Users/Marcela/Documents/Prime numbers to 100", line 13, in loopfunction
    while index <= 200000000.0:
RuntimeError: maximum recursion depth exceeded in cmp

Here is the script:

from __future__ import division
import sys
index=100000000.0
checker=2.0



def loopfunction():
    global index
    global checker
    checker=2

    while index <= 200000000.0:

        if index>=200000001:
            sys.exit(1)
        while checker<=14473.0:

            div = index/checker
            roundiv=round(index/checker, 0)
            if index == 1:
                print (index, "is prime")
                checker=2
                index=index+1
                loopfunction()   
            if checker == index:
                print (index, "is prime")
                checker=2
                index=index+1
                loopfunction()
            if roundiv==div:

                checker=2
                index=index+1
                loopfunction()    

            if checker==14473.0:

                print (index, "is prime")
                checker=2
                index=index+1
                loopfunction()

            checker = checker +1



loopfunction()

Upvotes: 0

Views: 1722

Answers (1)

Blckknght
Blckknght

Reputation: 104832

You can fix your recursion limit issue by simply not recursing. Your code already has the loops you need.

Just change the calls to loopfunction() in the various if statements to break.

While that is all that is needed to make the code function, I've noticed though that some of number of your if statements are unnecessary (either redundant with the loop conditions, or simply impossible to ever hit). You're also using while loops where for _ in range() loops would make more sense. Here's a greatly simplified version of your code, with some things renamed to clarify their purposes:

from math import sqrt

def primeFinder(start, end):
    prime = True

    for index in range(start, end):
        for checker in range(2, int(sqrt(index))+1):
            if index % checker == 0:
                prime = False
                break

        if prime:
            print("%d is prime" % index)

        prime = True

primetest(100000000, 200000001)

This version will still take a very long time (probably hours). If you really want to test a hundred million values for primeness, you should probably investigate a better algorithm, such as the Sieve of Eratosthenes.

Upvotes: 2

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