# Questions on the steay stokes equation with Dirchlet boundary conditions

Hi, I try to solve the above steady stokes equation with Dirichlet boundary conditions in the matrix form (Ax = b).

The vector b is implemented as

fespace Xh(Th, [P2, P2, P1]);
fespace Vh(Th, P2), Qh(Th, P1);
Vh u, v, c;
Qh p;
real delta = 0.8;
macro usx() dx(c)-( dx(c)*N.x+dy(c)*N.y )*N.x //
macro usy() dy(c)-( dx(c)*N.x+dy(c)*N.y )*N.y //
varf bcl( [u, v, p], [uu, vv, pp] ) = on(C1, u=usx, v=usy) + on(C2, u=0, v=0);
real[int] b = bcl(0, Xh);

I can not obtain correct results using the above codes. I also try the following codes:
(1)

macro usx(c) dx(c)-( dx(c)*N.x+dy(c)*N.y )*N.x //
macro usy(c) dy(c)-( dx(c)*N.x+dy(c)*N.y )*N.y //

(2)

func usx = dx(c)-( dx(c)*N.x+dy(c)*N.y )*N.x;
func usy = dy(c)-( dx(c)*N.x+dy(c)*N.y )*N.y;

but none of them can give the desired results.

I would appreciate it if anyone could give me some suggestions on how to implement the Dirichlet boundary conditions. thanks in advance.