astro-float 0.1.0

Astro-float (astronomically large floating point numbers) is a library that implements arbitrary precision floating point numbers purely in Rust.

The library implements the basic operations and functions. It uses classical algorithms such as Karatsuba, Toom-3, Schönhage-Strassen algorithm, and others.

The library can work without the standard library provided there is a memory allocator.

Usage

Below is an example of using the library. For more information please refer to the library documentation: https://docs.rs/astro-float/latest/astro_float/

Calculate Pi with 1024 bit precision:

use astro_float::BigFloatNumber;
use astro_float::PI;
use astro_float::RoundingMode;
use astro_float::Radix;
use astro_float::Error;

// Rounding of all operations
let rm = RoundingMode::ToEven;

// Compute pi: pi = 6*arctan(1/sqrt(3))
let six = BigFloatNumber::from_word(6, 1).unwrap();
let three = BigFloatNumber::parse("3.0", Radix::Dec, 1024+8, rm).unwrap();  // +8 bits of precision to cover error
let mut pi = six.mul(&three.sqrt(rm).unwrap().reciprocal(rm).unwrap().atan(rm).unwrap(), rm).unwrap();
pi.set_precision(1024, rm).unwrap();
let mut epsilon = BigFloatNumber::from_word(1, 1).unwrap();
epsilon.set_exponent(-1021);

// Use library's constant for verifying the result
let pi_lib = PI.with(|v| -> Result<BigFloatNumber, Error> {
    v.borrow_mut().for_prec(1024, rm)
}).unwrap();

// Compare computed constant with library's constant
assert!(pi.sub(&pi_lib, rm).unwrap().abs().unwrap().cmp(&epsilon) <= 0);

// Print computed result as decimal number.
let s = pi.format(Radix::Dec, rm).unwrap();
println!("{}", s);

// output: 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593344612847564823378678316527120190914564856692346034861045432664821339360726024914127372458698858e+0

Performance

Benchmark can be found here: https://github.com/stencillogic/bigfloat-bench.

Roadmap

Future improvements include the implementation of faster mathematical function algorithms for arguments with large precision, such as AGM implementation for calculating the logarithm, and faster trigonometric functions.

Contributing

The library is still young and may lack some features or contain bugs. Issues for these or other cases can be opened here: https://github.com/stencillogic/astro-float/issues