bigdecimal 0.4.2

Arbitrary precision decimal numbers


crate Documentation

minimum rustc 1.43

codecov build status - master build status - trunk

Arbitary-precision decimal numbers implemented in pure Rust.


Add bigdecimal as a dependency to your Cargo.toml file:

bigdecimal = "0.4"

Import and use the BigDecimal struct to solve your problems:

use bigdecimal::BigDecimal;

fn main() {
    let two = BigDecimal::from(2);
    println!("sqrt(2) = {}", two.sqrt().unwrap());

this code will print

sqrt(2) = 1.414213562373095048801688724209698078569671875376948073176679737990732478462107038850387534327641573

Default precision

Default precision may be set at compile time with the environment variable RUST_BIGDECIMAL_DEFAULT_PRECISION. The default value of this variable is 100.

This will be used as maximum precision for operations which may produce infinite digits (inverse, sqrt, ...).

Note that other operations, such as multiplication, will preserve all digits, so multiplying two 70 digit numbers will result in one 140 digit number. The user will have to manually trim the number of digits after calculations to reasonable amounts using the x.with_prec(30) method.

A new set of methods with explicit precision and rounding modes is being worked on, but even after those are introduced the default precision will have to be used as the implicit value.


Work is being done on this codebase again and there are many features and improvements on the way.


This repository contains code originally meant for a bigdecimal module in the popular num crate, but was not merged due to uncertainty of what the best design for such a crate should be.


This code is dual-licensed under the permissive MIT & Apache 2.0 licenses.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


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