245.sagews

# Graph for 16.2 #27
# ------------------

var('x,y,t')
F = plot_vector_field((x-y,x*y),(x,-2.5,2.5),(y,-2.5,2.5),pivot='middle')
C = parametric_plot((2*cos(t),2*sin(t)),(t,0,3*pi/2))
(F + C).show(figsize=[5,5])