axiolid-evaluate

Analytic and spline curve/surface evaluation, jets, and inversion.

Latest release	0.3.22 (2026-11-14)
crates.io	axiolid-evaluate
Facade	axiolid feature evaluate
Layer	algorithms (algorithm.parametric)
API documentation	rustdoc · docs.rs
Source	crates/algorithms/parametric/evaluate/

Overview

The scalar evaluation oracle for parametric geometry (ADR 0012, ADR 0036): native-domain evaluation of analytic and B-spline curves and surfaces, derivatives, jets, adaptive flattening, elementary surface inversion, arc-length evaluation of intrinsic (natural-equation) and elevated curves and of arc-length chains, arc length and its inverse on any curve, the section frames of banked curves, the derivatives and certified chord and derivative bounds of elevated and banked curves in plan distance (over an intrinsic plan with certified points, #393), certified chord bounds of the pcurves a section is read through (graphs, implicit and intrinsic curves, lifted curves and pair sections, #414), stations (a section frame at a distance along a curve, or along pieces of curves laid end to end), and ReferenceCurveEvaluator, the reference implementation of the curve-evaluation contract (ADR 0063). It has no mesh, spatial, measure or provider dependency, so a parametric consumer gets evaluation without the axiolid-reference umbrella. It favours obvious correctness over speed: no intrinsics, threading or feature gates.

Depends on

• axiolid-contracts
• axiolid-core
• axiolid-curve
• axiolid-curve-evaluate-contract
• axiolid-surface

Changes

Latest release, 0.3.22 (2026-11-14):

Added

• bound::ChainPositionTable and bound::SeamSide (#438): certified points, unit tangents and curvature vectors of an arc-length chain, read in any order, each with a bound on its distance from the exact one. The exact chain is the representation's: an intrinsic piece's points come from an IntrinsicPositionTable; a line, circle, ellipse or B-spline piece is read at the parameter whose certified arc length (chord panels) encloses the distance, the evaluator's inverse only a guess that is bisected when its enclosure misses; placements carry the position and the turn error from piece to piece. A parametric piece may start up to PIECE_FRAME_TOLERANCE off its local origin: a read at a join takes the piece that starts there (SeamSide::Outgoing, what the evaluator reads) or the piece that ends there (SeamSide::Incoming). None for a family without a certified arc length, a piece longer than its curve and a budget that runs out.
• bound::ElevatedPositionTable takes an elevated or banked curve over a chain plan (#438; 0.3.21 returned None for one): the plan is read from a ChainPositionTable. point3_on(d, side) reads a join from either side, jet3_on returns the point with the first and second derivatives (the plan's from the chain table, the profile's and the pivot's in closed form; over an intrinsic plan the curve's own, bit for bit) and jet_errors bounds how far the three can be from the exact ones.

Changed

• chain::chain_certifies is false for a chain with a parametric piece other than a line, a circle, an ellipse or a B-spline (a sinusoid or a polyline, #438): no certified arc length exists to charge its evaluated ends against, so flatten2 no longer claims such a chain.
• bound::certifies_flattening3 claims an elevated curve over a chain plan again, exactly where chain_certifies does (#438; 0.3.21 refused it, #393, because its chord bound under-reported the evaluated ends).

Fixed

• chain::chain_chord_bound, bound::chord_bound2 over a chain and bound::chord_bound3 of an elevated or banked curve over a chain plan bound the distance to the chord of the evaluated ends (#438): the exact-chord bound plus the larger distance of an evaluated end from a certified ChainPositionTable point, the lower end read as the piece that starts there, the upper end as the piece that ends there. They reported only the exact chord: 1.95e-5 over [116.4375, 116.5625] of a chain of a line and k = 0.01 sin(50 s), where the exact curve lies 2.835e-3 from the chord of the evaluated ends, and 0 for a point span whose evaluated point is 1.4e-2 off; a parametric piece that starts off the end of the one before it (up to PIECE_FRAME_TOLERANCE) is charged its jump.
• curve::flatten2 and flatten3 no longer accept a span of a claimed family (certifies_flattening2/3) whose chord bound is None on its sagitta alone (#438): the span is refined and, at the depth limit, refused with BudgetExceeded. A chain under a stretched start frame (stretch 2 or 4) had its table refuse reads near its own bound, because a rounding allowance grew with the square of the stretch; the resulting None bounds passed as proven and the polyline lay 3.9e-3 from the curve at a 3e-3 tolerance.

Full history: crates/algorithms/parametric/evaluate/CHANGELOG.md