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Angelos Chalaris
2019-07-19 09:17:16 +03:00
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Checks if the number is prime or not. Returns True if passed number is prime, and False if not. Checks if the number is prime or not. Returns True if passed number is prime, and False if not.
The function uses Fermat's theorem. First, it picks the number A in range 1..(n-1), then it checks if A to the power of n-1 modulo n equals 1. If not, the number is not prime, else it's pseudoprime with probability 1/2. Appling this test k times we have probability 1/(2^k). For example, if the number passes the test 10 times, we have probability 0.00098. The function uses Fermat's theorem.
First, it picks the number `A` in range `1`..`(n-1)`, then it checks if `A` to the power of `n-1` modulo `n` equals `1`.
If not, the number is not prime, else it's pseudoprime with probability 1/2. Applying this test `k `times we have probability `1/(2^k)`.
For example, if the number passes the test `10` times, we have probability `0.00098`.
``` python ``` python
from random import randint from random import randint