keplerian 0.2.0

Domain-agnostic Keplerian dynamics: typed anomaly solvers, elements, propagation, Lambert, and transfer search.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50

// SPDX-License-Identifier: AGPL-3.0-only
// Copyright (C) 2026 Vallés Puig, Ramon

//! Private numeric helpers for `[f64; 3]` vector algebra.
//!
//! ## Scientific scope
//! These helpers implement Euclidean 3-vector operations used internally by
//! Keplerian element conversion and Lambert solving.
//!
//! ## Technical scope
//! The functions are crate-private and operate only on raw arrays. Public APIs
//! remain typed through `qtty` and `affn`.
//!
//! ## References
//! - Battin, R. H. (1999). *An Introduction to the Mathematics and Methods of
//!   Astrodynamics*.

/// Dot product of two raw 3-vectors.
#[inline]
pub(crate) fn dot(a: [f64; 3], b: [f64; 3]) -> f64 {
    a[0] * b[0] + a[1] * b[1] + a[2] * b[2]
}

/// Cross product of two raw 3-vectors.
#[inline]
pub(crate) fn cross(a: [f64; 3], b: [f64; 3]) -> [f64; 3] {
    [
        a[1] * b[2] - a[2] * b[1],
        a[2] * b[0] - a[0] * b[2],
        a[0] * b[1] - a[1] * b[0],
    ]
}

/// Euclidean norm of a raw 3-vector.
#[inline]
pub(crate) fn norm(a: [f64; 3]) -> f64 {
    dot(a, a).sqrt()
}

/// Scalar multiplication on a raw 3-vector.
#[inline]
pub(crate) fn scale(a: [f64; 3], s: f64) -> [f64; 3] {
    [a[0] * s, a[1] * s, a[2] * s]
}

/// Difference `a - b` on raw 3-vectors.
#[inline]
pub(crate) fn sub(a: [f64; 3], b: [f64; 3]) -> [f64; 3] {
    [a[0] - b[0], a[1] - b[1], a[2] - b[2]]
}