Mathematics¶

mil_tools.rotate_vect_by_quat(v: List[float], q: List[float]) → ndarray[source]¶

Rotates a vector by a quaterion using v' = q*vq. Both v and q should be a list of 4 floats representing [x, y, z, w].

Parameters

Returns

The numpy array representing the new calculated quaternion.

Return type

np.ndarray

mil_tools.skew_symmetric_cross(vector: List[float]) → ndarray[source]¶

Returns the skew symmetric matrix representation of a vector.

Parameters: a (List[float]) – The vector to find the skew symmetric matrix representation of.
Returns: The skew-symmetric cross product matrix of the vector.
Return type: np.ndarray

mil_tools.deskew(matrix: ndarray[Any, dtype[ScalarType]]) → ndarray[source]¶

Finds the original vector from its skew-symmetric cross product. Finds the reverse of mil_tools.skew_symmetric_cross().

Parameters: matrix (List[float]) – The matrix to find the original vector from.
Returns: The original vector.
Return type: numpy.typing.NDArray

mil_tools.normalize(vector) → ndarray[Any, dtype[ScalarType]][source]¶

Normalizes a vector by dividing a non-zero vector by the vector norm.

Parameters: vector (numpy.typing.ArrayLike) – An array to compute the normal vector of.
Returns: The normalized vector.
Return type: numpy.typing.NDArray

mil_tools.compose_transformation(rotation: ndarray[Any, dtype[ScalarType]], translation: ndarray[Any, dtype[ScalarType]]) → ndarray[source]¶

Compose a transformation from a rotation matrix and a translation matrix.

Parameters

rotation (np.ndarray) – The rotation to add to the final transformation matrix.
translation (np.ndarray) – The translation to add to the final transformation matrix.

Returns

The transformation matrix.

Return type

np.ndarray

mil_tools.make_rotation(vector_a: List[float], vector_b: List[float]) → ndarray[Any, dtype[ScalarType]][source]¶

Determine a 3D rotation that rotates A onto B. In other words, we want a matrix R that aligns A with B.

>>> R = make_rotation(a, b)
>>> p = R.dot(a)
>>> np.cross(p, a)
array([0.0, 0.0, 0.0])

mil_tools.quat_to_rotvec(quat: List[float]) → ndarray[source]¶

Convert a quaternion to a rotation vector.

Parameters: quat (List[float]) – An array representing the quaternion.
Returns: The new rotation vector.
Return type: np.ndarray

mil_tools.euler_to_quat(rotvec: List[float]) → Quaternion[source]¶

Convert a euler rotation vector into a ROS Quaternion message.

Parameters: rotvec (List[float]) – The rotation vector to form into the Quaternion message.
Returns: The newly constructed Quaternion message.
Return type: Quaternion