> with(plots):with(plottools):
> fieldplot([x,y],x=-3..3,y=-3..3);
> fieldplot3d([x,y,z],x=-3..3,y=-3..3,z=-3..3);
> fieldplot([x,0],x=-3..3,y=-3..3);
> fieldplot([y,-x],x=-3..3,y=-3..3);
> fieldplot([y,x],x=-3..3,y=-3..3);
> fieldplot([x,x^2],x=-3..3,y=-3..3);
> #Vector Field is [F(x,y),G(x,y)]
> #So my system is 
> F:=x;G:=y;eqns:={diff(y(t),t)=y(t),diff(x(t),t)=x(t),y(0)=2,x(0)=3};
> F:=x;G:=0;eqns:={diff(y(t),t)=0,diff(x(t),t)=x(t),y(0)=2,x(0)=3};
> F:=y;G:=-x;eqns:={diff(y(t),t)=-x(t),diff(x(t),t)=y(t),y(0)=2,x(0)=3};
> F:=y;G:=x;eqns:={diff(y(t),t)=x(t),diff(x(t),t)=y(t),y(0)=2,x(0)=3};
> F:=x;G:=x^2;eqns:={diff(y(t),t)=(x(t))^2,diff(x(t),t)=x(t),y(0)=2,x(0)=3};
> a:=fieldplot([F,G],x=-5..5,y=-5..5):a;
> #Solve the ODE initial value problem
> s:=dsolve(eqns,{x(t),y(t)});
> s:=dsolve(eqns,{x(t),y(t)},type=numeric);
> b:=odeplot(s,[x(t),y(t)],-1..1,view=[-5..5,-5..5],color=green):b;
> c:=pointplot([3,2],color=red):c;
> display(a,b,c,scaling=constrained);
> #Let's show some parametric eqns
> r:=t->[cos(t),sin(t),t/(2*Pi)];
> rprime:=unapply(diff(r(t),t),t);
> a:=spacecurve(r(t),t=0..6*Pi,numpoints=1000):a;
> n:=20;f:=i->i*6*Pi/n;
> b:=seq(arrow(r(f(i)),r(f(i))+rprime(f(i)),.1,.1,.2,color=green),i=0..20):
> for i from 1 to 21 do P[i]:=display(a,b[i]):od:
> display(seq(P[i],i=1..21),insequence=true);
> spacecurve([cos(3*t),sin(5*t),0],t=0..2*Pi,numpoints=2000);
> int(sqrt(diff(cos(3*t),t)^2+diff(sin(5*t),t)^2),t=0..2*Pi);
> evalf(int(sqrt(diff(cos(3*t),t)^2+diff(sin(5*t),t)^2),t=0..2*Pi));
> T:=x^2+y^2+z^2;diff(T,x,x)+diff(T,y,y)+diff(T,z,z);