way # 1 - with Stokes' ie, int_C F dot ds = int int_S curl(F) dot dS
> restart : with(linalg):
Warning, new definition for norm
Warning, new definition for trace
> F_1 := 3*z;
> F_2 := 5*x;
> F_3 := -2*y;
> F := [ F_1, F_2, F_3 ];
> curl_F := curl( F , [x,y,z] );
> n := [0, -1, 1] / norm( [0, -1, 1] , 2) ;
> intgrand := dotprod( curl_F , n );
S is an ellipse with center (0,0,3) and semi-axes of length a & b where:
> center := [ 0,0,3];
> c_y := [ 0 , 1, 4 ];
> c_x := [ 1 , 0, 3 ];
> b := norm( c_y - center , 2);
> a := norm( c_x - center , 2);
So using problem #3 from this exam:
> surface_area_of_S := Pi * a* b;
and so since the integrand is constant:
> integral := intgrand * surface_area_of_S ;
>