x 2 x 2) array of jacobian matrices (jacobian matrix at
        triangle first apex)
        *ecc* is a (N x 3 x 1) array (array of column-matrices of triangle
        eccentricities)
        *dofs* is a (N x 1 x 9) arrays (arrays of row-matrices) of computed
        degrees of freedom.

        Returns
        -------
        Returns the values of interpolated function derivatives [dz/dx, dz/dy]
        in global coordinates at locations alpha, as a column-matrices of
        shape (N x 2 x 1).
        r"