warp.quat\_twist\_angle\_signed
===============================

.. currentmodule:: warp._src.lang

.. function:: quat_twist_angle_signed(axis: vec3f, q: quatf) -> float

   .. wp-function-tags::
      :kernel: true
      :python: true
      :differentiable: true
      :source: https://github.com/NVIDIA/warp/blob/release-1.19/warp/_src/math.py#L197-L218

   Return the signed twist angle in radians of ``q`` around ``axis``.
   
   Unlike :func:`quat_twist_angle`, this preserves the sign of the twist, so
   rotations by ``+theta`` and ``-theta`` around ``axis`` return opposite
   values. Positive angles follow the right-hand rule about ``axis``.
   
   :param axis: Twist axis, with unit length.
   :param q: Rotation quaternion.
   
   :returns: Signed twist angle in radians, in ``[-pi, pi]`` if ``q[3] >= 0`` and
             in ``[-2*pi, 2*pi]`` otherwise, so ``q`` and ``-q`` can return different
             angles even though they represent the same rotation. It is unspecified
             when ``q`` is a rotation of 180 degrees about an axis perpendicular to
             ``axis``.
   :rtype: float