tree acc936511d6bd2cb0293ed8e43d06e573bef74bf
parent 76b431ef0495776f9cce48dd4d212927c3c0c627
author Sergiu Deitsch <sergiu.deitsch@gmail.com> 1777635403 +0200
committer Sergiu Deitsch <sergiu.deitsch@gmail.com> 1785524438 +0200
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Restore quaternion group action

Commit 370631f01f71db36b580e5a65790b2a8d9559821 rescaled the quaternion
manifold's group action so the tangent vector norm matches the full
rotation angle, addressing issue #941. While both conventions are
mathematically valid, issue #311 already concluded that the half-angle
one should be kept because too much code depends on it. The rescaling
effectively broke that expectation for existing callers.

Restore the pre-370631f01f71db36b580e5a65790b2a8d9559821 scaling, keep
the rest of that commit's cleanup, and update the documentation and
tests to match.

Fixes #1190

Change-Id: I1dd189c51153ed62cc8c871472aacb87673ec351