Hello everyone.

I am currently trying to plot the displacements solutions of my code as a surface. If I understand, the function ‘u’(displacements, solution) must be u = u(x,y) since I’m using a 2d mesh. This is how I defined u:

```
V = FunctionSpace(mesh, 'CG',1)
u = Function(V, name='Displacement')
```

This works if I want to know any specific value of u, but I tried to implement a surface plot as it follows:

```
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
Xp = np.arange(-0.5, 0.5, 0.01)
Yp = np.arange(0, 1, 0.01)
Xp, Yp = np.meshgrid(Xp, Yp)
up = u(Xp,Yp)
surf = ax.plot_surface(Xp, Yp, up, cmap=cm.coolwarm, linewidth=0, antialiased=False)
fig.colorbar(surf, shrink=0.5, aspect=5)
plt.show
----------------
Traceback (most recent call last):
File "Robin_Neumann_Edu.py", line 197, in <module>
up = u(Xp,Yp)
File "/usr/lib/petsc/lib/python3/dist-packages/dolfin/function/function.py", line 345, in __call__
raise TypeError("expected scalar arguments for the coordinates")
TypeError: expected scalar arguments for the coordinates
```

Xp and Yp are vectors whose components are scalars, so, why is this problem happening? Shouldn’t up be the value of u in every (Xp, Yp)?

Thanks again.