BDDC: Fix block sizes (#4253)

Author: pbrubeck

firedrake/preconditioners/fdm.py

@@ -777,10 +777,11 @@ def setup_block(self, Vrow, Vcol):
         P.setISAllowRepeated(self.allow_repeated)
         P.setLGMap(rmap, cmap)
         if on_diag and ptype == "is" and self.allow_repeated:
-            bsize = Vrow.finat_element.space_dimension() * Vrow.value_size
+            bsize = Vrow.finat_element.space_dimension() * Vrow.block_size
             local_mat = P.getISLocalMat()
             nblocks = local_mat.getSize()[0] // bsize
-            local_mat.setVariableBlockSizes([bsize] * nblocks)
+            sizes = numpy.full((nblocks,), bsize, dtype=PETSc.IntType)
+            local_mat.setVariableBlockSizes(sizes)
         P.setPreallocationNNZ((dnz, onz))
 
         if not (ptype.endswith("sbaij") or ptype == "is"):

tests/firedrake/regression/test_bddc.py

@@ -111,8 +111,8 @@ def solve_riesz_map(mesh, family, degree, bcs, condense):
 
 @pytest.fixture(params=(2, 3), ids=("square", "cube"))
 def mesh(request):
-    nx = 4
     dim = request.param
+    nx = 4
     msh = UnitSquareMesh(nx, nx, quadrilateral=True)
     if dim == 3:
         msh = ExtrudedMesh(msh, nx)
@@ -126,5 +126,5 @@ def mesh(request):
 def test_bddc_fdm(mesh, family, degree, condense):
     bcs = True
     tdim = mesh.topological_dimension()
-    expected = 6 if tdim == 2 else 11
+    expected = 7 if tdim == 2 else 11
     assert solve_riesz_map(mesh, family, degree, bcs, condense) <= expected