quaternion-core

Quaternion library written in Rust.

This provides basic operations on Quaternion and conversions to and from several attitude representations as generic functions (Supports f32 & f64).

Usage

Add this to your Cargo.toml:

[dependencies]
quaternion-core = "0.2"

Conversion

conversion

Interconversion with 24 different Euler angles (12 each of Intrinsic and Extrinsic) is possible!!

Features

Cargo.toml:

[dependencies.quaternion-core]
version = "0.2"

# Uncomment if you wish to use FMA and SIMD.
#features = ["fma", "simd"]

# Uncomment if you wish to use in "no_std" environment.
#default-features = false
#features = ["libm"]

The `fma` feature

This library uses the mul_add method mainly to improve the performance, but by default it is replace with a unfused multiply-add (s*a + b) . If you wish to use mul_add method, enable the fma feature.

If your CPU does not support FMA instructions, or if you use libm (running in no_std environment), enabling the fma feature may cause slowdown of computation speed. Also, due to rounding error, results of s.mul_add(a, b) and s*a + b will not match perfectly.

The `simd` feature

Attension!! : This feature may have bugs and should not be enabled at first.

By enabling this feature, the SIMD implementation using the std::arch module can be used in some functions.

Currently (version="0.2.0") only x86 and x86_64 architectures are supported.

To enable this feature, CPU must support these instruction sets:

SSE, SSE2, SSE3, SSE4.1, AVX, FMA

Also, specify the -C target-cpu flag to the compiler as follows:

$ RUSTFLAGS='-C target-cpu=native' cargo build

The `libm` feature and `default-feature = false`

These options allow for use in the no_std environment. In this case, mathematical functions (e.g. sin, cos, sqrt ...) are provided by libm.

Example

src/main.rs:

use quaternion_core as quat;

const PI: f64 = std::f64::consts::PI;
const EPSILON: f64 = 1e-14;

fn main() {
    // Point
    let r = [2.0, 2.0, 0.0];

    // Generates a quaternion representing the
    // rotation of π/2[rad] around the y-axis.
    let q = quat::from_axis_angle([0.0, 1.0, 0.0], PI/2.0);

    let result = quat::point_rotation(q, r);

    // Check if the calculation is correct.
    let diff = quat::sub_vec([0.0, 2.0, -2.0], result);
    for val in diff {
        assert!( val.abs() < EPSILON );
    }
}

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.

Contribution

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.

quaternion-core 0.2.0