We can use the following code, which works to have the solution of the equation:
def F(x): ... return np.cos(x) + x[::-1] - [1, 2, 3, 4] import scipy.optimize x = scipy.optimize.broyden1(F, [1,1,1,1], f_tol=1e-14) x array([ 4.04674914, 3.91158389, 2.71791677, 1.61756251]) np.cos(x) + x[::-1] array([ 1., 2., 3., 4.])