text: #!/usr/bin/env python3
  
  import numpy as np
  
  A = np.array([
      [ 0,  2,  1],
      [ 1, -2, -3],
      [-1,  1,  2]])
  
  x = np.array([-4, -5, 2])
  
  y = A.dot(x)
  
  print(A)
  print(x)
  print(y)
  print(x.T.dot(A.T).T)
  