Assign values to component of W.sub(0)

Question

if mixed function space W = V*Q, where V is a vector function space, and I want to set the value of second component of V to zero, can we access it as (W.sub(0)).sub(1) ?

Is it possible to set the value using V and then create W ?

Answer 1

Should be straight forward. Something like this should do it:

# Get the scalar FunctionSpace corresponding to V 
S = FunctionSpace(mesh, V.ufl_element().family(), V.ufl_element().degree())    
u0 = interpolate(Expression("x[0]"), S)

# Get Function on W and assign u0 to second component of V
u = Function(W)
assign(u.sub(0).sub(1), u0)

Comments

Thank you for the answer. That is very useful to know. However, I realized I had completely misrepresented my question. I have submitted a new question for it.