Good day! I have the next question: Is it any difference between putting in the equation expression and expression, interpolated on function space (i.e. function)? Example bellow. Thank you!

```
from dolfin import *
mesh = UnitSquareMesh(30, 30)
V = FunctionSpace(mesh, "CG", 1)
def boundary(x, on_boundary):
return on_boundary
u_D = Expression('1 + x[0] * x[0] + 2 * x[1] * x[1]', degree=2)
bc = DirichletBC(V, u_D, boundary)
u = TrialFunction(V)
v = TestFunction(V)
f = Expression('-6.0', degree=1)
# f = interpolate(Expression('-6.0', degree=1), V) Is it matter?
a = dot(grad(u), grad(v)) * dx
L = f * v * dx
u = Function(V)
solve(a == L, u, bc)
```