Example of a Conservative Vector Field

> with(plots):

> P:=y^2+3*y*exp(3*x);

> Q:=1+2*x*y+exp(3*x);

> fieldplot([P,Q],x=-1..0,y=-2..2,color=blue,grid=[10,10]);

> fieldplot([P,Q],x=0..1,y=-2..2,color=blue,grid=[10,10]);

>