* Property-based and hostile-input tests for geometry numerics (gaps.md S6)
A deterministic xorshift64* generator (no new dependency) drives a few
thousand cases per property in crates/geom/src/property_tests.rs:
- line/line: hits lie on both lines, parameters reproduce the point,
swapping the operands gives the same point, finite results agree with
the infinite parameters
- line/circle and circle/circle: hits lie on both curves, results are
symmetric, properly crossing circles match the closed form; hostile
inputs (NaN, infinities, subnormals, raw bit patterns, 1e300) never
panic and the guarded functions return only finite hits or none
- segments: extending only adds hits
- closest points: fixed point of closest, perpendicular inside the
segment, endpoints outside
- arcs: at(0)/at(1) are the endpoints at radii from 1e-6 to 1e6; the
three-point arc keeps {start, end} = {p1, p3} and contains p2 (the
CCW-only storage swaps the pair when p2 is on the clockwise side, as
DXF stores arcs) and matches the circumradius closed form; collinear
inputs are rejected
- bounds and vector identities
- known answers at 1e6-1e7 coordinates hold to 1e-9 relative
gaps.md S6 removed and geometry-parity.md's Tests section updated in
the same change.
* docs: drop the sentence the new numerics tests make stale
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---------
Co-authored-by: Brandon Thomas <echelon@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
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