Example 2: Example 2 (p. 678)
> f := y^2-x^2;
> g := x^2/4+y^2-1;
>
> Pobj := plot3d( f, x=0..3, y=0..3 ):
> Pobj;
> Pcon := implicitplot3d( g=0, x=0..2,y=0..2,z=0..5, color=cyan, style=patchnogrid ):
> Pcon;
>
> display( Pobj, Pcon );
>
> fx := diff( f, x );
> fy := diff( f, y );
> gx := diff( g, x );
> gy := diff( g, y );
>
> LE := fx=lambda*gx, fy=lambda*gy;
> LEsol := solve( {LE,g=0}, {x,y,lambda} );
>
>
> sol := {seq( eval( [x,y], s ), s=LEsol )};
>