from pylab import *

xvalues, yvalues = meshgrid(arange(0, 3, 0.1), arange(0, 3, 0.1))

xdot =   xvalues - xvalues * yvalues
ydot = - yvalues + xvalues * yvalues

streamplot(xvalues, yvalues, xdot, ydot)

show()
