# insert code here




from numpy import random
from numpy import matrix

A = matrix( random.rand( 4,3 ) )
x = matrix( random.rand( 3,1 ) )
y = matrix( random.rand( 4,1 ) )
yold = matrix( random.rand( 4,1 ) )

print( 'A before =' )
print( A )

print( 'x before =' )
print( x )

print( 'y before =' )
print( y )

laff.copy( y, yold )   # save the original vector y

Mvmult_n_unb_var1( A, x, y )

print( 'y after =' )
print( y )

print( 'y - ( A * x + yold ) = ' )
print( y - ( A * x + yold ) )