Changelog

All notable changes to lambert_izzo are documented here. The format follows Keep a Changelog, and the project follows Semantic Versioning.

Unreleased

solveLambert no longer throws on solver failure. It now returns the same LambertOutcome tagged union that solveLambertBatch returns per element, so single-call and batch JS callers share one pattern-match shape: result.kind === "ok" → result.response, result.kind === "err" → result.error (a structured LambertErrorOutput). The Rust core's Result<T, LambertError> API is unchanged.
BatchResult renamed to LambertOutcome. It is the per-solve outcome type used by both entry points and is no longer batch-specific.

Migration: replace try { const r = solveLambert(req); … } catch (e) { … } with const result = solveLambert(req); if (result.kind === "ok") { … } else { … }. Existing solveLambertBatch callers only need to change the imported type name from BatchResult to LambertOutcome (the runtime shape is identical).

Initial public release. lambert_izzo is a no_std-friendly Rust implementation of Izzo's revisited Lambert solver (arXiv:1403.2705).

Single-revolution and multi-revolution (short- and long-way) Lambert solves via lambert(&LambertInput) -> Result<LambertSolutions, LambertError>.
Three-regime time-of-flight dispatch — Battin hypergeometric series near the parabolic point, Lancaster–Blanchard in the transitional zone, Lagrange elsewhere — with all thresholds documented in constants.rs.
Cubic Householder iteration with derivative-matched starters (Izzo Eq. 30, 31) and Halley T_min search for multi-revolution feasibility detection.
Round-trip Kepler validation via a universal-variable Stumpff propagator; examples/stress.rs runs 100,000 single-rev plus 100,000 multi-rev randomized trials with vis-viva and angular-momentum conservation checks.

[f64; 3] for all positions and velocities — no hard math-library dependency. nalgebra::Vector3<f64> and glam::DVec3 convert natively.
Unit-agnostic: pass any consistent unit system. Documented SI convention is km / km/s / s / km³/s².
Frame-invariant: the solver returns velocities in whatever inertial frame the inputs are in (ECI, HCRS, MCI, ...). Frame info lives at the call site, not in field names.
LambertError is a flat thiserror enum with structured fields (Position, NonFiniteParameter, RevsOutOfRange); zero unwrap/expect/panic! in lib code, mechanically enforced by clippy denials.
Multi-rev capacity is bounded at compile time via BoundedRevs (newtype around NonZeroU32, 1..=32); the cap is statically asserted to match MAX_MULTI_REV_PAIRS. No heap allocation on the solver hot path.
Diagnostics (Householder iteration counts) ride along on every LambertSolutions — no separate "with-diagnostics" entry point.

serde — derives Serialize / Deserialize on every public type, including LambertError. Stays no_std-compatible.
rayon — enables lambert_par(&[LambertInput]), a parallel batch solver. Pulls std transitively; not no_std-compatible.

lambert_izzo — the canonical Rust crate. no_std-friendly, [f64; 3]-only public surface.
lambert_izzo_wasm — wasm-bindgen adapter exposing JavaScript / TypeScript request and response types via tsify. Errors map to a tag-discriminated union; a forward-compat Unknown { message } variant guards against future core variants. Publishes to npm as lambert-izzo, version-locked to the workspace Cargo.toml — npm version matches the crates.io version.
lambert_izzo_test_support — workspace-internal dev fixtures (publish = false): SI body constants, rejection-sampling unit vectors, deterministic batch generator, universal-variable Kepler propagator. Used as a [dev-dependencies] path crate by the core's examples, benches, and tests.

MSRV: Rust 1.85 (first edition-2024 stable).
Examples: demo, stress, errors, batch (rayon-gated), and serde (serde-gated).
Benches: single_rev, batch, and multi_rev (parametrized across M ∈ {1, 3, 5} via Criterion's bench_with_input); a multi_rev_battin group exercises the Battin near-parabolic regime (|x − 1| < BATTIN_THRESHOLD) via a near-180° geometry with TOF jittered around the parabolic time-of-flight.
CI: GitHub Actions workflow at .github/workflows/ci.yml covering MSRV (1.85) build × four feature combos, full build/test/doctest on stable × four feature combos, clippy, docs (with RUSTDOCFLAGS: -D warnings), wasm32 build for lambert_izzo and lambert_izzo_wasm, the stress example, and a markdown link-check pass via lychee (lychee.toml).
Dual-licensed MIT OR Apache-2.0.