Assign a function profile to a function in a mixed space

General
1

Hello,
Given the mixed space defined as follows

P_z = FiniteElement('P', triangle, 1)
P_omega = VectorElement('P', triangle, 1)
element = MixedElement([P_z, P_omega])
Q_z_omega = FunctionSpace(mesh, element)

and the function

z_omega = Function(Q_z_omega)
z, omega = split(z_omega)

I want to assign to the z part of z_omega a given function profile, derived from the analytical expression x^2/2\, y^2/2. I tried

class z_Expression(UserExpression):
    def eval(self, values, x):
        values[0] = ((x[0])**2)/2.0 * ((x[1])**2)/2.0
    def value_shape(self):
        return (1,)
z = interpolate(z_Expression(element=Q_z.ufl_element()), Q_z)

But the assignement z = interpolate ... seems to have no effect. How may I assign to the z part of z_omega the function x^2/2\, y^2/2 ?
(please not that I am not using dolfinx)

Thanks

1 Like
2

Can you try with something like

z, omega = split(z_omega)
z_new = interpolate(z_Expression(element=Q_z.ufl_element()), Q_z)
z.assign(z_new)

Overwrite the name z is certainly wrong, as it doesn’t assign the storage in z_omega, simply changes the name of the python variable z.

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