Quaternion to Euler Scipy Implementation

It contains the implementation of the method described in https://doi.org/10.1371/journal.pone.0276302. for the direct conversion of a rotation Quaternion into Euler angles of any given sequence.

Note: sadly, the original paper was published with some typos in the equations. For an updated version with the correct equations, check Chapter 10 of my PhD thesis manuscript.

This implementation is heavily based in the older Scipy implementation.

Unit tests

All the necessary unit tests showing the correctedness of the algorithm can be seen in the the Scipy implementation: github.com/scipy/.../test_rotation.py.

This algorithm has been integrated in the following projects:

• Sympy
• SciPy
• pytransform3d

Contents:

• euler_from_quat.py: Implementation of the method in Scipy-based code style.
• main.py: Execution time comparison of both methods.

Little warning:

On the PLOS ONE paper, I am following the convention of real part as the first element (like SymPy, for example.)

In this implementation, I am following SciPy's convention of the real part as the last element.

This means that, for example, a rotation around axis x of angle 90 degrees should be:

q = np.asarray([[1/sqrt(2), 0, 0, 1/sqrt(2)]])

Instead of:

q = np.asarray([[1/sqrt(2), 1/sqrt(2), 0, 0]])