import numpy as np
from scipy.sparse import diags_array, issparse
from scipy.sparse.linalg import spsolve

n = 5
A = diags_array(
    [-np.ones(n - 1), 4 * np.ones(n), -np.ones(n - 1)],
    offsets=[-1, 0, 1],
    shape=(n, n),
    format="csr",
)
b = np.array([2.0, 1.0, 0.0, 1.0, 2.0])