Assign expression to function

Question

Hi,

Is it possible to assign an expression to a Function defined on a FunctionSpace?

E.g. With the following

mesh = UnitSquareMesh(32, 32)
V = FunctionSpace(mesh, "CG", 1)
u = Function(V)

f = Expression("x[0]+x[1]")

Is there a way to assign u the expression f, while still keeping u a Function()?

johanhake · Answer 1 · Jun 11, 2014

Best answer

You can interpolate it:

u.interpolate(f)

answered Jun 11, 2014 by johanhake FEniCS Expert (22,480 points)
selected Jun 12, 2014 by sixtysymbols

print  u.interpolate(f).vector().array()
AttributeError: 'NoneType' object has no attribute 'vector'

Am I doing something wrong ?

commented Jun 15, 2014 by shriram FEniCS User (1,540 points)
reshown Jun 15, 2014 by johanhake

Yes, try:

u.interpolate(f)
u.vector().array()

commented Jun 15, 2014 by johanhake FEniCS Expert (22,480 points)

1 Answer