fdecimal

Arbitrary-precision fast decimal numbers implemented in pure Rust.

lib.rs:

Decimal

Decimal allows storing real number to arbitrary precision; which avoids common floating point errors (such as 0.1 + 0.2 ≠ 0.3) at the cost of complexity.

Internally, Decimal uses a 256-bit integer, paired with a 64-bit integer which determines the position of the decimal point. Therefore, the precision is not actually arbitrary, but limited to 2⁶³ decimal places.

Common numerical operations are overloaded, so we can treat them the same way we treat other numbers.

It is not recommended to convert a floating point number to a decimal directly, as the floating point representation may be unexpected.

Example

use fdecimal::Decimal;
use std::str::FromStr;

let input = "0.8";
let dec = Decimal::from_str(&input).unwrap();
let float = f32::from_str(&input).unwrap();

println!("Input ({}) with decimals: {} vs {})", input, dec, float);