import numpy as np
import numpy.linalg as linalg

A = np.array( 
    [
        [ 4.0, -2.0,  1.0],
        [-2.0,  4.0, -2.0],
        [ 1.0, -2.0,  3.0] 
    ] 
)
b = np.array( [1.0, 4.0, 2.0] )
print(np.dot(A,b))
linalg.inv(A)
linalg.det(A)
linalg.solve(A, b)
