Function fermat 

pub fn fermat(num: &BigUint) -> bool

Performs a probabilistic primality test using Fermat’s little theorem.

Fermat’s little theorem states that if p is a prime number, then for any integer a such that 1 < a < p - 1, the number a^(p-1) is congruent to 1 modulo p. This function tests the primality of num using a set of base witnesses (2, 3, 5, 7, 11, 13, 17, 19, 23, 29).

Note that passing this test does not guarantee that num is prime, but failing it guarantees that num is composite. Thus, this function can produce false positives, but not false negatives.

Arguments

• num - A reference to a BigUint representing the number to test for primality.

Returns

• true if num passes the Fermat primality test for all witnesses.
• false if num fails the test for any witness, or if num is less than or equal to 1.

Examples

use num_bigint::BigUint;
use large_primes::fermat;
 
let number = BigUint::parse_bytes(b"97", 10).unwrap();
assert!(fermat(&number));

let non_prime = BigUint::parse_bytes(b"100", 10).unwrap();
assert!(!fermat(&non_prime));