Quaternions
Composition, inverse, normalization, relative orientation, axis-angle conversion, SLERP, and vector rotation.
Rotation mathematics · C ABI · Explicit conventions
The orientation layer beneath estimation and control.
This library keeps quaternion, Euler-angle, direction-cosine-matrix, and vector transformations in one small C boundary. The goal is not merely to produce numbers, but to make ordering, handedness, rotation direction, normalization, and singularities reviewable.
orientation input→checked transformation→quaternion / DCM / Euler→estimation + control
One mathematical foundation
DCMs and Euler angles
Checked conversions, orthonormality checks, supported rotation orders, and explicit singularity behavior.
Vectors and utilities
Dot, cross, normalization, magnitudes, angle wrapping, and unit conversion used by downstream numerical systems.