commit ba8d967f8c13a52dd552c7b69ba0eb171f04fbc5
author Sameer Agarwal <sameeragarwal@google.com> Tue Oct 02 00:48:57 2012 -0700
committer Sameer Agarwal <sameeragarwal@google.com> Fri Oct 05 08:35:53 2012 -0700
tree 191dea33f1f5fa1c3c63c7bc94d6a029ce6a3cc6
parent 2c94eed50fe4606ff115674a9616e379343a2f26

Generalization of the inner iterations algorithm.

Add automatic recursive independent set decomposition.
Clean up the naming and the API for inner iterations.

Change-Id: I3d7d6babb9756842d7367e14b7279d2df98fb724

internal/ceres/trust_region_minimizer.cc

diff --git a/internal/ceres/trust_region_minimizer.cc b/internal/ceres/trust_region_minimizer.cc
index b838b19..db2641d 100644
--- a/internal/ceres/trust_region_minimizer.cc
+++ b/internal/ceres/trust_region_minimizer.cc
@@ -340,11 +340,30 @@
         LOG(WARNING) << "Step failed to evaluate. "
                      << "Treating it as step with infinite cost";
         new_cost = numeric_limits<double>::max();
-      } else if (new_cost < cost && options.inner_iteration_minimizer != NULL) {
-        Solver::Summary inner_iteration_summary;
-        options.inner_iteration_minimizer->Minimize(options,
-                                                    x_plus_delta.data(),
-                                                    &inner_iteration_summary);
+      } else {
+        // Check if performing an inner iteration will make it better.
+        if (options.inner_iteration_minimizer != NULL) {
+          const double x_plus_delta_cost = new_cost;
+          Vector inner_iteration_x = x_plus_delta;
+          Solver::Summary inner_iteration_summary;
+          options.inner_iteration_minimizer->Minimize(options,
+                                                      inner_iteration_x.data(),
+                                                      &inner_iteration_summary);
+          if(!evaluator->Evaluate(inner_iteration_x.data(),
+                                  &new_cost,
+                                  NULL, NULL, NULL)) {
+            VLOG(2) << "Inner iteration failed.";
+            new_cost = x_plus_delta_cost;
+          } else {
+            x_plus_delta = inner_iteration_x;
+            // Bost the model_cost_change, since the inner iteration
+            // improvements are not accounted for by the trust region.
+            model_cost_change +=  x_plus_delta_cost - new_cost;
+            VLOG(2) << "Inner iteration succeeded; current cost: " << cost
+                    << " x_plus_delta_cost: " << x_plus_delta_cost
+                    << " new_cost: " << new_cost;
+          }
+        }
       }
 
       iteration_summary.step_norm = (x - x_plus_delta).norm();