Hi team, I run into a "NotImplemented" exception when trying to assign values to an function on extruded mesh of 1 layer. I'm wondering is it really not implemented or (more likely) just my bad usage? The situation is that I have this function on DG(0) x CG(1), and I just need to assign values to the top and bottom surfaces. Many thanks! -TJ code: --------------------------------------------------------------------------- m = RectangleMesh(5,5,5,5,quadrilateral=True) mesh = ExtrudedMesh(m, layers=1) W_h = FiniteElement("DG", "quadrilateral", 0) W_v = FiniteElement("CG", "interval", 1) W_elt = TensorProductElement(W_h, W_v) W = FunctionSpace(mesh, W_elt) # This Expression reads values from an array class Ex_intensity(Expression): def eval(self, value, X): # this is not quite completed, there will be more logic here x0 = int(X[0]) x1 = int(X[1]) value[:] = p0[x1,x0] I = Function(W) I.interpolate(Ex_intensity()) I.at(2.5,2.5,0) Error message: --------------------------------------------------------------------------- NotImplementedError Traceback (most recent call last) <ipython-input-12-055ffdeb8731> in <module>() ----> 1 I.at(2.5,2.5,0) /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/firedrake/function.pyc in at(self, arg, *args, **kwargs) 492 else: 493 p_result = np.empty(value_shape, dtype=float) --> 494 single_eval(points[i:i+1], p_result) 495 l_result.append((i, p_result)) 496 except PointNotInDomainError: /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/firedrake/function.pyc in single_eval(x, buf) 470 def single_eval(x, buf): 471 """Helper function to evaluate at a single point.""" --> 472 err = self._c_evaluate(self._ctypes, 473 x.ctypes.data_as(POINTER(c_double)), 474 buf.ctypes.data_as(POINTER(c_double))) /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/utils.pyc in __get__(self, obj, cls) 62 if obj is None: 63 return self ---> 64 obj.__dict__[self.__name__] = result = self.fget(obj) 65 return result 66 /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/firedrake/function.pyc in _ctypes(self) 406 else: 407 c_function.n_layers = 1 --> 408 c_function.coords = coordinates.dat.data.ctypes.data_as(POINTER(c_double)) 409 c_function.coords_map = coordinates_space.cell_node_list.ctypes.data_as(POINTER(c_int)) 410 c_function.f = self.dat.data.ctypes.data_as(POINTER(c_double)) <decorator-gen-136> in data(self) /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/versioning.pyc in modifies(method, self, *args, **kwargs) 113 _force_copies(self) 114 --> 115 retval = method(self, *args, **kwargs) 116 117 self._version_bump() /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/base.pyc in data(self) 1759 1760 """ -> 1761 _trace.evaluate(set([self]), set([self])) 1762 if self.dataset.total_size > 0 and self._data.size == 0 and self.cdim > 0: 1763 raise RuntimeError("Illegal access: no data associated with this Dat!") /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/base.pyc in evaluate(self, reads, writes) 169 to_run = fuse('from_trace', to_run, 0) 170 for comp in to_run: --> 171 comp._run() 172 173 /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/base.pyc in _run(self) 4073 4074 def _run(self): -> 4075 return self.compute() 4076 4077 def prepare_arglist(self, iterset, *args): /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/base.pyc in compute(self) 4115 arglist = self.prepare_arglist(iterset, *self.args) 4116 fun = self._jitmodule -> 4117 self._compute(iterset.core_part, fun, *arglist) 4118 self.halo_exchange_end() 4119 self._compute(iterset.owned_part, fun, *arglist) /home/ts2914/projects/firedrake/local/lib/python2.7/site-packages/pyop2/pyparloop.pyc in _compute(self, part, *arglist) 106 def _compute(self, part, *arglist): 107 if part.set._extruded: --> 108 raise NotImplementedError 109 subset = isinstance(self._it_space._iterset, base.Subset) 110 NotImplementedError: