Assemble for variational form of cross product of normal and testfunction

1

Hi Sir,
i am not able to assemble the variational form

mesh=UnitSquareMesh(1,1)
V=FunctionSpace(mesh, "Nedelec 1st kind H(curl)", 1)

u=TrialFunction(V)
v=TestFunction(V)

a=inner(u,v)*dx
b=inner(curl(u), curl(v))*dx

n=FacetNormal(mesh)
c=inner(cross(n,v), cross(n, u))*ds

f=Constant((1,0))
d=inner(f,v)*dx


A=assemble(a)
B=assemble(b)
C=assemble(c)

error is

Calling FFC just-in-time (JIT) compiler, this may take some time.
Index out of bounds.
Traceback (most recent call last):
  File "vec1.py", line 55, in <module>
    C=assemble(c)
  File "/usr/lib/petsc/lib/python3/dist-packages/dolfin/fem/assembling.py", line 202, in assemble
    dolfin_form = _create_dolfin_form(form, form_compiler_parameters)
  File "/usr/lib/petsc/lib/python3/dist-packages/dolfin/fem/assembling.py", line 60, in _create_dolfin_form
    return Form(form,
2

It might be that your vectors in the cross product are not three dimensional.
Check this post and this answer: