Function mod_pow 

pub fn mod_pow(
    base: impl Into<BigInt>,
    exp: impl Into<BigInt>,
    modulus: impl Into<BigInt>,
) -> BigInt

Modular exponentiation: base^exp mod modulus.

Returns 0 if modulus ≤ 0 or exp < 0. Works for non-negative exponents.

Examples

use symplex::ntheory::mod_pow;
use num_bigint::BigInt;

assert_eq!(mod_pow(2, 10, 1000), BigInt::from(24));  // 1024 mod 1000
assert_eq!(mod_pow(3, 4, 17), BigInt::from(13));     // 81 mod 17