vecmath library: TVec2/3/4 + TMat with operator overloads — Track B

• Type: feature (library) — Track B
• Status: done bignum — nice library legwork that is testable, and we all love more tests"), sibling of [[feature-pascal-complex-numbers-ucomplex]]
• Owner: fable-p

What

lib/rtl/vecmath.pas: TVec2/TVec3/TVec4 (Double fields), TMat3/TMat4. Operators: + - * (vec op vec componentwise, vec op scalar, matmat, matvec), =; functions Dot, Cross (3D), NormSq, Norm, Normalize, Lerp, mat identity/translate/scale/rotate, Transpose, Determinant (3x3/4x4). v / scalar waits on [[feature-pascal-operator-slash-overload]] (VScale meanwhile). Overload dispatch keys on the LEFT operand → scalar*vec not registrable; provide function form and document.

Why

Real demo fuel (the E-track games/GUI apps want this) AND a deliberate operator-overloading workout — the feature has 2 thin tests today; matrices give it record-result chains ((a*b)*v + w), const params, nested record fields. Every identity is exactly testable.

Tests

lib-suite golden test: algebraic identities with exact expected output — cross(x̂,ŷ)=ẑ, dot orthogonality, |normalize(v)|=1, M·M⁻¹ spot checks (integer-friendly cases to dodge FP noise), mat*vec against hand-computed vectors, operator chains. Integer-valued inputs keep expected strings exact (FP-determinism rules).

Gate

Track B: build with $(PXX_STABLE), make lib-test green. Frontend gaps → P-lane ticket, don't patch here.

Log

• 2026-07-11 — resolved, commit 32758fcc.