puremp

Pure-Rust, MIT-licensed, arbitrary-precision arithmetic — integers, rationals, and MPFR-class floating point — with no foreign-code dependencies. Usable as a Rust crate, a C library, and a command-line calculator.

Status: early scaffold. The integer and rational layers are implemented and tested; the fast algorithms (sub-quadratic multiply/divide, subquadratic GCD) and the floating-point arithmetic layer are on the way. See ROADMAP.md for the design and milestone plan.

Why

A GMP + MPFR-class toolkit that is:

• Pure, safe Rust — no C, no inline assembly, no intrinsics. The only unsafe in the crate is the opt-in C ABI module.
• Clean-room & MIT-licensed — algorithms come from the open literature (Knuth; Brent & Zimmermann's Modern Computer Arithmetic; the HAC), never from GMP/MPFR source. Use it anywhere, including closed-source projects.
• no_std + alloc — runs on bare metal with an allocator; no OS assumptions in the core. Verified on 32-bit thumbv7em-none-eabi in CI.

Quick start (Rust)

[dependencies]
puremp = "0"

use puremp::{Int, Rational};

let big = Int::from_i64(2).pow(100);
assert_eq!(big.to_string(), "1267650600228229401496703205376");

let sum = Rational::new(Int::from_i64(1), Int::from_i64(2))?   // 1/2
    .add(&Rational::new(Int::from_i64(1), Int::from_i64(3))?); // + 1/3
assert_eq!(sum.to_string(), "5/6");
# Ok::<(), puremp::Error>(())

Quick start (CLI)

$ cargo run --bin puremp
puremp> 2 ** 100
1267650600228229401496703205376
puremp> x = 1000
puremp> x * x - 1
999999
puremp> (2**64) * (2**64)
340282366920938463463374607431768211456
puremp> :quit

Supports + - * / % **, parentheses, unary minus, decimal literals, and name = expr variables (/ and % are truncated integer division).

Quick start (C)

Build the static and/or shared library and link against the header in include/puremp.h:

$ cargo rustc --lib --release --features ffi --crate-type staticlib
$ cargo rustc --lib --release --features ffi --crate-type cdylib
$ cc myprog.c -I include target/release/libpuremp.a -lpthread -ldl -lm -o myprog

#include "puremp.h"
#include <stdio.h>

int main(void) {
    PurempInt *two = puremp_int_from_i64(2);
    PurempInt *big = puremp_int_pow(two, 100);
    char *s = puremp_int_to_string(big);
    printf("2^100 = %s\n", s);
    puremp_string_free(s);
    puremp_int_free(big);
    puremp_int_free(two);
    return 0;
}

Feature flags

For a bare no_std build: --no-default-features (add --features int for the integer types).

License

MIT — see LICENSE.