code: def to_rot_matrix(r):
      "Convert combined axis angle vector to rotation matrix"
      theta = np.linalg.norm(r)
      v = r/theta
      R = crisp.rotations.axis_angle_to_rotation_matrix(v, theta)
      return f to_rot_matrix(r):
      "Convert combined axis angle vector to rotation matrix"
      theta = np.linalg.norm(r)
      v = r/theta
      R = crisp.rotations.axis_angle_to_rotation_matrix(v, theta)
      return R
docs: Convert combined axis angle vector to rotation matrix