Weird behavior in to_DCM and from_DCM in Quaternion class about ahrs HOT 2 OPEN

    @staticmethod
    def from_DCM(mat):
        """ Returns the quaternion corresponding to the unitary DCM matrix. """
        mat = np.array(mat)
        tr = np.trace(mat)
        d = 1 + 2 * mat.diagonal() - tr
        qsquare = 1 / 4 * np.array([1 + tr, d[0], d[1], d[2]])
        qsquare = qsquare.clip(0, None)  # avoid numerical errors
        # compute signs matrix
        signs = np.sign([mat[1, 2] - mat[2, 1], mat[2, 0] - mat[0, 2], mat[0, 1] - mat[1, 0],
                         mat[0, 1] + mat[1, 0], mat[2, 0] + mat[0, 2], mat[1, 2] + mat[2, 1]])
        signs_m = np.zeros((4, 4))
        signs_m[np.triu_indices(4, 1)] = signs
        signs_m += signs_m.T
        signs_m[np.diag_indices(4)] = 1.
        # choose appropriate signs
        max_idx = qsquare.argmax()
        coords = np.sqrt(qsquare) * signs_m[max_idx]
        return Quaternion(*coords)