Xsum in Rust

This crate implments xsum algorithm by Radford M. Neal (https://arxiv.org/abs/1505.05571).

xsum is able to calculate fast exact summation

⚠️ Currently, xsum supports f64 calculation only.

Usage

add_list() to take vector or array

Calculates the sum of a small-sized vector or array.

use xsum::{Xsum, XsumSmall};

let mut xsmall = XsumSmall::new();
xsmall.add_list(&vec![1.0, 2.0, 3.0]);
assert_eq!(xsmall.sum(), 6.0);

Calculates the sum of a large-sized vector or array (more than 1,000 elements).

use xsum::{Xsum, XsumLarge};

let mut xlarge = XsumLarge::new();
xlarge.add_list(&vec![1.0; 1_000]);
assert_eq!(xlarge.sum(), 1000.0);

Calculates the sum of a unknown-sized vector or array.

use xsum::{Xsum, XsumAuto};

let mut xauto = XsumAuto::new();
xauto.add_list(&vec![1.0; 1_000]);
assert_eq!(xauto.sum(), 1000.0);

add() to take a floating point number

use xsum::{Xsum, XsumSmall};

let mut xsmall = XsumSmall::new();
let vec = vec![1.0, 2.0, 3.0];
for v in vec {
    xsmall.add(v);
}
assert_eq!(xsmall.sum(), 6.0);

Chaining Method

use xsum::{Xsum, XsumExt};

let vec = vec![1.0, 2.0, 3.0];
assert_eq!(vec.xsum(), 6.0);

Variant

If you already know the input size in advance, you can directly select the most suitable xsum variant, avoiding unnecessary overhead.

use xsum::{Xsum, XsumVariant, XsumAuto, XsumLarge, XsumSmall, constants::XSUM_THRESHOLD};

let vec = vec![1.0; 2_000];
let mut xVariant = if vec.len() < XSUM_THRESHOLD {
  XsumVariant::Small(XsumSmall::new())
} else {
  XsumVariant::Large(XsumLarge::new())
};
xVariant.add_list(&vec);
assert_eq!(xVariant.sum(), 2_000.0);

Safety

This crate sets unsafe_code = "forbid" in Cargo.toml to ensure that only safe Rust is used.

Documentation

The doc can be found on docs.rs.