3908.sagews

var('x y')
g(x,y)=y/x

VL=plot_vector_field(g.gradient(),(x,-1,-.3),(y,-1,1), color='red',plot_points=13)
VR=plot_vector_field(g.gradient(),(x,.3,1),(y,-1,1), color='red',plot_points=13)
show(VL+VR, figsize=5)

WL = plot3d(g,(x,-1,-.1),(y,-1,1), aspect_ratio=[1,1,.1], adaptive=True,color=['red','yellow']) 
WR = plot3d(g,(x,.1,1),(y,-1,1), aspect_ratio=[1,1,.1], adaptive=True,color=['red','yellow']) 
show(WL+WR, figsize=5)

CL= contour_plot(g,(x,-1,-.1),(y,-1,1), cmap='hsv',fill=False, contours=10) 
CR= contour_plot(g,(x,.1,1),(y,-1,1), cmap='hsv',fill=False, contours=10) 
show(CL+CR , figsize=5)

show(CL+CR+VL+VR, figsize=5)