# Evgenii B. Rudnyi, http://MatrixProgramming.com

from numpy import *
from scipy.linalg import *
a = array(
 [[-2,   1,   0,   0],
	[1,   -2,   1,   0],
	[0,    1,  -2,   1],
	[0,    0,   1,  -2]])
fac = cho_factor(-a)
print cho_solve(fac, array([2,1,1,2]))