separately delete forward dft chunk for adjoint optimization (#2251)

* separately delete forward dft chunk

* fix

* swig fix

* dft_fields::delete_dft_chunks

* declaration

* remove()

* clean up

* Update python/adjoint/optimization_problem.py

* trailing whitespace

Co-authored-by: Mo Chen <mochen@Mos-MacBook-Pro.local>
Co-authored-by: Steven G. Johnson <stevenj@mit.edu>

python/adjoint/optimization_problem.py

@@ -304,6 +304,12 @@ def calculate_gradient(self):
             for ar in range(len(self.objective_functions))
         ]
 
+        for dri in range(self.num_design_regions):
+            for i in range(3):
+                # note that dft_fields::remove calls delete on its chunks, and the
+                # destructor ~dft_chunk automatically removes it from the fields object
+                self.forward_design_region_monitors[dri][i].remove()
+
         # Cleanup list of lists
         if len(self.gradient) == 1:
             self.gradient = self.gradient[0]  # only one objective function

src/meepgeom.cpp

@@ -2999,7 +2999,6 @@ void material_grids_addgradient(double *v, size_t ng, size_t nf,
   for (int i = 0; i < 3; i++) {
     for (int ii = 0; ii < adjoint_dft_chunks[i].size(); ii++) {
       delete adjoint_dft_chunks[i][ii];
-      delete forward_dft_chunks[i][ii];
     }
   }