Numerical evidence

Equivalent representations must reconstruct the same orientation.

Validation covers ordinary rotations, 180-degree cases, gimbal-lock neighborhoods, quaternion/DCM/Euler reconstruction, vector rotation, relative orientation, and invalid-input rejection.

Deterministic C fixtures

Heap-free fixtures make the same mathematical cases available to host tests and eventual embedded integration.

Independent oracle

SciPy supplies a separately implemented rotation system for randomized parity rather than comparing one local function against another.

Failure behavior

Checked APIs reject unsupported orders, non-finite values, reflections, malformed DCMs, and zero-magnitude normalization.

cmake -S . -B build
cmake --build build
ctest --test-dir build --output-on-failure

Board builds and hardware execution are integration evidence. They do not replace mathematical parity, and a successful cross-compile is not a hardware pass.