mark tape before evaluating TLM, and start hessian accumulation from correct type (#190)

Author: JHopeCollins

pyadjoint/drivers.py

@@ -61,9 +61,12 @@ def compute_hessian(J, m, m_dot, options=None, tape=None):
         m[i].tlm_value = m_dot[i]
 
     with stop_annotating():
-        tape.evaluate_tlm()
+        with tape.marked_nodes(m):
+            tape.evaluate_tlm(markings=True)
+
+    J.block_variable.hessian_value = J.block_variable.output._ad_convert_type(
+        0., options={'riesz_representation': None})
 
-    J.block_variable.hessian_value = 0.0
     with stop_annotating():
         with tape.marked_nodes(m):
             tape.evaluate_hessian(markings=True)

pyadjoint/tape.py

@@ -361,11 +361,11 @@ def evaluate_adj(self, last_block=0, markings=False):
             ):
                 self._blocks[i].evaluate_adj(markings=markings)
 
-    def evaluate_tlm(self):
+    def evaluate_tlm(self, markings=False):
         for i in self._bar("Evaluating TLM").iter(
             range(len(self._blocks))
         ):
-            self._blocks[i].evaluate_tlm()
+            self._blocks[i].evaluate_tlm(markings=markings)
 
     def evaluate_hessian(self, markings=False):
         for i in self._bar("Evaluating Hessian").iter(