[PawelTroka]

Problem

isUnitary(matrix({{1,0}})) currently returns true. Its rows are orthonormal, but the rectangular map discards a coordinate and is not a unitary matrix. The same defect exists in the host and emitted TSL helper.

Change

Require equal row and column counts before applying the existing conjugate-transpose product and relative comparison. Preserve square-matrix arithmetic, the 1e-10 tolerance, input matrices, and the separate rectangular identity-pattern semantics of isIndentity / IdentityMatrix.

Update the authored and materialized reference together. This intentionally changes the previously documented rectangular-row behavior. A script that needs row orthonormality can continue to request it explicitly with isIndentity(M*HermitianTranspose(M)).

Validation

• 44 new portable cases: 15 failed and 29 passed against unchanged master; all 44 pass after the fix.
• Full portable Engine suite: 1,482 passed, zero failed/skipped. Rerun after recovery with SDK 10.0.403 on Linux x64.
• Tests cover host and complete emitted source, real/complex dense/sparse matrices, rectangular row-isometries, square rotations, complex conjugation, nonunitary inputs, nonfinite values, comparison tolerance, and actual TSL expression/script execution.
• 57 Python reference-authoring tests passed. Deterministic regeneration changes exactly one article; the other 1,219 stay identical.
• Six additional checks cover the shipped precompiled scripting facade in Windows Core.Tests. A Windows Core.Tests cross-build passed on this exact source tree; native Windows execution remains a CI gate.
• Independent code/compatibility review and git diff --check passed.

The uploaded tree 0b4c9131ff209eb4f53fe45792b744e49f935f65 exactly matches the tested local tree.

dotnet test Computator.NET.Engine.Tests/Computator.NET.Engine.Tests.csproj -c Release
python3 -m unittest discover -s build/reference -p 'test_*.py'

Existing work

Reviewed all 78 open issues, 14 existing open PRs, recent closed PRs, and targeted matrix/unitary searches. No existing PR repairs this predicate. This is separate from pointwise operations (#185), matrix powers (#238), and the active numerical/platform work.

Independently based on master fe1aba49b5f9538355ffaaa3d1683f69a23d2d9c. Draft for review and native CI; no merge performed.

Combined compatibility check — 2026-10-30

Also tested the final contributions in #311, #313, #314 and #315 together with the seven existing maintenance PRs (#304–#310), using the existing #312 candidate 189d28c0ec7acbf77d380f14f95ef450e7bfbd84 as the local integration base.

• Complete combined Engine Release suite: 1,819 passed, zero failed/skipped.
• Combined Python reference-authoring suite: 76 passed.
• Windows-targeted Core.Tests and Desktop.Tests cross-builds: passed, zero errors, with existing warnings.
• Deterministic reference check: passed, covering 1,251 articles and 1,351 completion items.

Eight shared paths required composition resolutions. These preserved all Euclid/ODE/polynomial aliases, completion and authoring registrations; Debye/unitary documentation; and Find/Replace/printing methods, test-source links and documentation entries. No feature behavior or numerical algorithm needed changing to combine the contributions. The independently published PRs remain based on master.

Combined local tree: 63225a973ea2883974a91ab26afcdc83d866e77b, SDK 10.0.403, Linux x64. The reference check used the authenticated master inventory plus current production reflection for changed entries through a portable UI shell. Native Windows tests, full native catalog execution and printer acceptance remain pending. The existing #312 PR was not changed by this local verification.