My own numerical system implementation

Question

I'm working with my own 91-numbers numerical system (unnonagesimal) in python 3.6 for RSA algorithm for my studies project. It works really fine but not with large numbers. Numbers I need it to work with are bigger than 1024 bits.

It doesn't work with some numbers, especially with those big ones.

The question is: Why doesn't it work?

Here's my code:

_unnonagesimal = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^/*?&<>()[]@%$#,;'`~|\"\\_"

def unnonagesimal_to_decimal(s):
    return sum([_unnonagesimal.find(var) * len(_unnonagesimal) ** i
                    for i, var in enumerate(reversed(s))])

def decimal_to_unnonagesimal(n):
    if n == 0:
        return 0
    else:
        s = ""
        while n != 0:
            s += _unnonagesimal[n % len(_unnonagesimal)]
            n = int(n / len(_unnonagesimal))

        return s[::-1]

Where:

unnonagesimal_to_decimal(s) converts unnonagesimal string s into a decimal number.

and

decimal_to_unnonagesimal(n) converts decimal int n into an unnonagesimal number.

Hello, can you explain what it's supposed to do and why it does not work? — Axnyff, Mar 28 '18 at 23:15
Hello, I just edited. Below code is explanation. I don't know why it does work with numbers like 234423 but doesn't work with 6354372758237865 — SecurityBreach, Mar 28 '18 at 23:18
Not sure what "it doesn't work" is supposed to mean. I can encode and decode 6354372758237865 just fine. Can you describe the problem? — Aran-Fey, Mar 28 '18 at 23:19
I just find out the answer.The problem was with integer division. Thank you @user2357112 — SecurityBreach, Mar 28 '18 at 23:23
Okay, but it would still be a good idea to make the question clear and useful... There's no real point posting a self-answer if the question isn't comprehensible. — Aran-Fey, Mar 28 '18 at 23:24
See question [Base 62 conversion](https://stackoverflow.com/questions/1119722/base-62-conversion) for a useful example of something similar. — martineau, Mar 28 '18 at 23:42

SecurityBreach · Accepted Answer · 2018-03-29T00:12:05.323

Alright, I just find out thanks to @user2357112

The problem was with int(blah / blah). Corrected to int(blah // blah). Now works fine.

This problem was becasue I switched to python 3 from python 2. For anyone who doesn't know: in python 2, 5/2 = 2 but in python 3, 5/2 = 2.5 yet 5//2 = 2

I just thought dividing integers are the same in python 2 and 3.

Working code in python 3.6.5:

_unnonagesimal = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^/*?&<>()[]@%$#,;'`~|\"\\_"


def unnonagesimal_to_decimal(s):
    return sum([_unnonagesimal.find(var) * len(_unnonagesimal) ** i for i, var in enumerate(reversed(s))])


def decimal_to_unnonagesimal(n):
    if n == 0:
        return 0
    else:
        s = ""

        while n != 0:
            s += _unnonagesimal[n % len(_unnonagesimal)]
            n = int(n // len(_unnonagesimal))

        return s[::-1]

My own numerical system implementation

1 Answers1