Default variant for DPC elements (#457)

* DPC variants

* basix branch

* write dpc variant into generated code

* dolfinx branch

* dpc variant

* branch reset

* dolfinx branch

ffcx/codegeneration/finite_element.py

@@ -48,6 +48,11 @@ def generator(ir, parameters):
     else:
         d["lagrange_variant"] = int(ir.lagrange_variant)
 
+    if ir.dpc_variant is None:
+        d["dpc_variant"] = -1
+    else:
+        d["dpc_variant"] = int(ir.dpc_variant)
+
     if ir.basix_family is None:
         d["basix_family"] = -1
     else:

ffcx/codegeneration/finite_element_template.py

@@ -35,6 +35,7 @@
   .basix_cell = {basix_cell},
   .discontinuous = {discontinuous},
   .lagrange_variant = {lagrange_variant},
+  .dpc_variant = {dpc_variant},
   .num_sub_elements = {num_sub_elements},
   .sub_elements = {sub_elements}
 }};

ffcx/codegeneration/ufcx.h

@@ -134,6 +134,9 @@ extern "C"
     /// The Lagrange variant to be passed to Basix's create_element function
     int lagrange_variant;
 
+    /// The DPC variant to be passed to Basix's create_element function
+    int dpc_variant;
+
     /// Number of sub elements (for a mixed element)
     int num_sub_elements;
 

ffcx/element_interface.py

@@ -63,19 +63,24 @@ def create_element(element: ufl.finiteelement.FiniteElementBase) -> BaseElement:
     if family_name == "DPC":
         discontinuous = True
 
-    if family_name in ["Lagrange", "Q"]:
+    family_type = basix.finite_element.string_to_family(family_name, element.cell().cellname())
+    cell_type = basix.cell.string_to_type(element.cell().cellname())
+
+    if family_type == basix.ElementFamily.P:
         if element.variant() is None:
             variant_info.append(basix.LagrangeVariant.gll_warped)
         else:
             variant_info.append(basix.variants.string_to_lagrange_variant(element.variant()))
-    elif family_name in ["S", "serendipity"]:
+    elif family_type == basix.ElementFamily.serendipity:
         if element.variant() is None:
             variant_info.append(basix.LagrangeVariant.gll_warped)
         else:
             variant_info.append(basix.variants.string_to_lagrange_variant(element.variant()))
-
-    family_type = basix.finite_element.string_to_family(family_name, element.cell().cellname())
-    cell_type = basix.cell.string_to_type(element.cell().cellname())
+    elif family_type == basix.ElementFamily.DPC:
+        if element.variant() is None:
+            variant_info.append(basix.DPCVariant.diagonal_gll)
+        else:
+            variant_info.append(basix.variants.string_to_dpc_variant(element.variant()))
 
     return BasixElement(family_type, cell_type, element.degree(), variant_info, discontinuous)
 
@@ -249,6 +254,12 @@ def lagrange_variant(self):
         """Basix Lagrange variant used to initialise the element."""
         pass
 
+    @property
+    @abstractmethod
+    def dpc_variant(self):
+        """Basix DPC variant used to initialise the element."""
+        pass
+
     @property
     @abstractmethod
     def cell_type(self):
@@ -342,6 +353,10 @@ def element_family(self):
     def lagrange_variant(self):
         return self.element.lagrange_variant
 
+    @property
+    def dpc_variant(self):
+        return self.element.dpc_variant
+
     @property
     def cell_type(self):
         return self._cell
@@ -432,6 +447,10 @@ def element_family(self):
     def lagrange_variant(self):
         return self.element.lagrange_variant
 
+    @property
+    def dpc_variant(self):
+        return self.element.dpc_variant
+
     @property
     def cell_type(self):
         return self.element.cell_type
@@ -550,6 +569,10 @@ def reference_geometry(self):
     def lagrange_variant(self):
         return None
 
+    @property
+    def dpc_variant(self):
+        return None
+
     @property
     def element_family(self):
         return None
@@ -654,6 +677,10 @@ def reference_geometry(self):
     def lagrange_variant(self):
         return self.sub_element.lagrange_variant
 
+    @property
+    def dpc_variant(self):
+        return self.sub_element.dpc_variant
+
     @property
     def element_family(self):
         return self.sub_element.element_family
@@ -761,6 +788,10 @@ def family_name(self):
     def lagrange_variant(self):
         return None
 
+    @property
+    def dpc_variant(self):
+        return None
+
     @property
     def element_family(self):
         return None

ffcx/ir/representation.py

@@ -42,7 +42,7 @@
     'id', 'name', 'signature', 'cell_shape', 'topological_dimension',
     'geometric_dimension', 'space_dimension', 'value_shape', 'reference_value_shape', 'degree',
     'family', 'num_sub_elements', 'block_size', 'sub_elements', 'element_type', 'entity_dofs',
-    'lagrange_variant', 'basix_family', 'basix_cell', 'discontinuous'])
+    'lagrange_variant', 'dpc_variant', 'basix_family', 'basix_cell', 'discontinuous'])
 ir_dofmap = namedtuple('ir_dofmap', [
     'id', 'name', 'signature', 'num_global_support_dofs', 'num_element_support_dofs', 'num_entity_dofs',
     'tabulate_entity_dofs', 'num_entity_closure_dofs', 'tabulate_entity_closure_dofs', 'num_sub_dofmaps',
@@ -135,6 +135,7 @@ def _compute_element_ir(ufl_element, element_numbers, finite_element_names):
     ir["space_dimension"] = basix_element.dim
     ir["element_type"] = basix_element.element_type
     ir["lagrange_variant"] = basix_element.lagrange_variant
+    ir["dpc_variant"] = basix_element.dpc_variant
     ir["basix_family"] = basix_element.element_family
     ir["basix_cell"] = basix_element.cell_type
     ir["discontinuous"] = basix_element.discontinuous