Only calculate mask for fermion tensor im reverse edge.

tat/tensor.py

@@ -786,18 +786,20 @@ def reverse_edge(
             parity_exclude_names = set()
         assert all(name in self.names for name in reversed_names)
         assert all(name in reversed_names for name in parity_exclude_names)
-        # Parity is xor of all valid reverse parity
-        parity = functools.reduce(
-            torch.logical_xor,
-            (
-                _utility.unsqueeze(edge.parity, current_index, self.rank)
-                # Loop over all edge
-                for current_index, [name, edge] in enumerate(zip(self.names, self.edges))
-                # Check if this edge is reversed and if this edge will be applied parity
-                if (name in reversed_names) and (apply_parity ^ (name in parity_exclude_names))),
-            torch.zeros([], dtype=torch.bool),
-        )
-        data = torch.where(parity, -self.data, +self.data)
+        data = self.data
+        if any(self.fermion):
+            # Parity is xor of all valid reverse parity
+            parity = functools.reduce(
+                torch.logical_xor,
+                (
+                    _utility.unsqueeze(edge.parity, current_index, self.rank)
+                    # Loop over all edge
+                    for current_index, [name, edge] in enumerate(zip(self.names, self.edges))
+                    # Check if this edge is reversed and if this edge will be applied parity
+                    if (name in reversed_names) and (apply_parity ^ (name in parity_exclude_names))),
+                torch.zeros([], dtype=torch.bool),
+            )
+            data = torch.where(parity, -data, +data)
         return Tensor(
             names=self.names,
             edges=tuple(