Expand description
A Big integer (signed version: BigInt
, unsigned version: BigUint
).
A BigUint
is represented as a vector of BigDigit
s.
A BigInt
is a combination of BigUint
and Sign
.
Common numerical operations are overloaded, so we can treat them the same way we treat other numbers.
§Example
extern crate num_bigint;
extern crate num_traits;
use num_bigint::BigUint;
use num_traits::{Zero, One};
use std::mem::replace;
// Calculate large fibonacci numbers.
fn fib(n: usize) -> BigUint {
let mut f0: BigUint = Zero::zero();
let mut f1: BigUint = One::one();
for _ in 0..n {
let f2 = f0 + &f1;
// This is a low cost way of swapping f0 with f1 and f1 with f2.
f0 = replace(&mut f1, f2);
}
f0
}
// This is a very large number.
println!("fib(1000) = {}", fib(1000));
It’s easy to generate large random numbers:
extern crate rand;
extern crate num_bigint as bigint;
use bigint::{ToBigInt, RandBigInt};
let mut rng = rand::thread_rng();
let a = rng.gen_bigint(1000);
let low = -10000.to_bigint().unwrap();
let high = 10000.to_bigint().unwrap();
let b = rng.gen_bigint_range(&low, &high);
// Probably an even larger number.
println!("{}", a * b);
§Compatibility
The num-bigint
crate is tested for rustc 1.19 and greater.
Modules§
Structs§
Enums§
- Parse
BigInt Error - Sign
- A Sign is a
BigInt
’s composing element.
Constants§
Traits§
- Rand
BigInt - ToBig
Int - A generic trait for converting a value to a
BigInt
. - ToBig
Uint - A generic trait for converting a value to a
BigUint
.
Type Aliases§
- BigDigit
- A
BigDigit
is aBigUint
’s composing element. - Double
BigDigit - A
DoubleBigDigit
is the internal type used to do the computations. Its size is the double of the size ofBigDigit
.