x = b, given the LU factorization of a

    Parameters
    ----------
    (lu, piv)
        Factorization of the coefficient matrix a, as given by lu_factor
    b : array
        Right-hand side
    trans : {0, 1, 2}, optional
        Type of system to solve:

        =====  =========
        trans  system
        =====  =========
        0      a x   = b
        1      a^T x = b
        2      a^H x = b
        =====  =========
    overwrite_b : bool, optional
        Whether to overwrite data in b (may increase performance)
    check_finite : bool, optional
        Whether to check that the input matrices contain only finite numbers.
        Disabling may give a performance gain, but may result in problems
        (crashes, non-termination) if the inputs do contain infinities or NaNs.

    Returns
    -------
    x : array
        Solution to the system

    See Also
    --------
    lu_factor : LU factorize a matrix

    Examples
    --------
    >>> import numpy as np
    >>> from scipy.linalg import lu_factor, lu_solve
    >>> A = np.array([[2, 5, 8, 7], [5, 2, 2, 8], [7, 5, 6, 6], [5, 4, 4, 8]])
    >>> b = np.array([1, 1, 1, 1])
    >>> lu, piv = lu_factor(A)
    >>> x = lu_solve((lu, piv), b)
    >>> np.allclose(A @ x - b, np.zeros((4,)))
    True

    r