def deskew ( S ) : x = np . zeros ( 3 ) x [ 0 ] = S [ 2 , 1 ] x [ 1 ] = S [ 0 , 2 ] x [ 2 ] = S [ 1 , 0 ] return x
create skew symmetric matrix from a vector python
Converts a skew - symmetric cross - product matrix to its corresponding vector . Only works for 3x3 matrices .
def deskew(S):
    """Converts a skew-symmetric cross-product matrix to its corresponding
    vector. Only works for 3x3 matrices.

    Parameters
    ----------
    S : :obj:`numpy.ndarray` of float
        A 3x3 skew-symmetric matrix.

    Returns
    -------
    :obj:`numpy.ndarray` of float
        A 3-entry vector that corresponds to the given cross product matrix.
    """
    x = np.zeros(3)
    x[0] = S[2,1]
    x[1] = S[0,2]
    x[2] = S[1,0]
    return x