def gs_iter(initData, A=A0, bvec=bvec0):  # x = -[(L+D)^-1]*Ux + [(L+D)^-1]*b
    ld = Util.getLowerDiag(A)
    upper = A - ld
    sInv = Util.matrix_inverse(ld)
    return iterate(initData, sInv, upper, bvec)
def jacobi_iter(initData, A=A0, bvec=bvec0):  # x = -[D^-1](L+U)x + [D^-1]*b
    diagonal = Util.getDiag(A)
    lu = A - diagonal
    sInv = Util.matrix_inverse(diagonal)
    return iterate(initData, sInv, lu, bvec)