import numpy as np 
import matplotlib.pyplot as plt 

def vel(A, x, y):
    return A[0,0]*x + A[0,1]*y, A[1,0]*x + A[1,1]*y


# t = np.linspace(-1, 1, 40)
# x, y = np.meshgrid(t, t)

# A = np.matrix([[1,3],[3,1]])

# u, v = vel(A, x, y)

# plt.streamplot(x,y,u,v, color=np.sqrt(x**2 + y**2), cmap="jet")
# plt.quiver(x,y,u,v)
# plt.show()

B = np.matrix([[4,5],[-5,-2]])

t = np.linspace(-1, 1, 40)
x, y = np.meshgrid(t, t)

u, v = vel(B, x, y)

plt.streamplot(x,y,u,v, color=np.sqrt(u**2 + v**2), cmap="jet")
plt.show()