vecmat 0.7.8

Low-dimensional vector algebra with min_const_generics support
Documentation 
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use crate::{
    complex::{Complex, Moebius, Quaternion},
    distr::{Invertible, Normal, Unit},
};
use approx::*;
use rand_::prelude::*;
use rand_xorshift::XorShiftRng;

const SAMPLE_ATTEMPTS: usize = 256;

#[test]
fn chaining() {
    let mut rng = XorShiftRng::seed_from_u64(0xBEEF0);
    for _ in 0..SAMPLE_ATTEMPTS {
        let a: Moebius<Complex<f64>> = rng.sample(Invertible);
        let b: Moebius<Complex<f64>> = rng.sample(Invertible);
        let c: Quaternion<f64> = rng.sample(Normal);
        assert_abs_diff_eq!(a.chain(b).apply(c), a.apply(b.apply(c)), epsilon = 1e-12,);
    }
}

#[test]
fn complex_derivation() {
    let mut rng = XorShiftRng::seed_from_u64(0xBEEF1);
    const EPS: f64 = 1e-8;

    for _ in 0..SAMPLE_ATTEMPTS {
        let a: Moebius<Complex<f64>> = rng.sample(Invertible);
        let p: Complex<f64> = rng.sample(Normal);
        let v: Complex<f64> = rng.sample(Unit);

        let deriv = a.deriv(p);
        let dabs = deriv.norm();
        assert_abs_diff_eq!(
            (a.apply(p + EPS * v) - a.apply(p)) / (EPS * v),
            deriv,
            epsilon = 1e-4 * dabs
        );
    }
}

#[test]
fn quaternion_directional_derivation() {
    let mut rng = XorShiftRng::seed_from_u64(0xBEEF2);
    const EPS: f64 = 1e-8;

    for _ in 0..SAMPLE_ATTEMPTS {
        let a: Moebius<Complex<f64>> = rng.sample(Invertible);
        let p: Quaternion<f64> = rng.sample(Normal);
        let v: Quaternion<f64> = rng.sample(Unit);

        let deriv = a.deriv_dir(p, v);
        let dabs = deriv.norm();
        assert_abs_diff_eq!(
            (a.apply(p + EPS * v) - a.apply(p)) / EPS,
            deriv,
            epsilon = 1e-4 * dabs
        );
    }
}