comments

Author: pbrubeck

firedrake/assemble.py

@@ -526,11 +526,12 @@ def base_form_assembly_visitor(self, expr, tensor, *args):
                     raise ValueError("Expecting a scalar weight expression")
                 weights.append(w)
 
+            # Scalar FormSum
             if all(isinstance(op, numbers.Complex) for op in args):
-                result = sum(weight * arg for weight, arg in zip(weights, args))
+                result = numpy.dot(weights, args)
                 return tensor.assign(result) if tensor else result
 
-            # Compress repeated terms
+            # Accumulate coefficients in a dictionary for each unique Dat/Mat
             terms = defaultdict(int)
             for arg, weight in zip(args, weights):
                 t = self._as_pyop2_type(arg)
@@ -550,15 +551,17 @@ def base_form_assembly_visitor(self, expr, tensor, *args):
             else:
                 raise ValueError("Expecting tensor to be None, Function, Cofunction, or Matrix")
 
-            # Compute the sum
+            # Compute the linear combination
             if (all(isinstance(op, firedrake.Cofunction) for op in args)
                     or all(isinstance(op, firedrake.Function) for op in args)):
+                # Vector FormSum
                 V, = set(a.function_space() for a in args)
                 result = tensor if tensor else firedrake.Function(V)
                 dats, weights = zip(*terms.items())
                 result.dat.maxpy(weights, dats)
                 return result
             elif all(isinstance(op, ufl.Matrix) for op in args):
+                # Matrix FormSum
                 result = tensor.petscmat if tensor else PETSc.Mat()
                 for (op, w) in terms.items():
                     if result: