Added a minor optimization.

dlib/global_optimization/global_function_search.cpp

@@ -702,7 +702,23 @@ namespace dlib
         for (auto& info : functions)
         {
             const long dims = info->spec.lower.size();
-            if (info->ub.num_points() < std::max<long>(3,dims))
+            if (info->ub.num_points() < 1)
+            {
+                outstanding_function_eval_request new_req;
+                new_req.request_id = next_request_id++;
+                // Pick the point right in the center of the bounds to evaluate first since
+                // people will commonly center the bound on a location they think is good.
+                // So might as well try there first.
+                new_req.x = (info->spec.lower + info->spec.upper)/2.0;
+                for (long i = 0; i < new_req.x.size(); ++i)
+                {
+                    if (info->spec.is_integer_variable[i])
+                        new_req.x(i) = std::round(new_req.x(i));
+                }
+                info->outstanding_evals.emplace_back(new_req);
+                return function_evaluation_request(new_req,info);
+            }
+            else if (info->ub.num_points() < std::max<long>(3,dims))
             {
                 outstanding_function_eval_request new_req;
                 new_req.request_id = next_request_id++;

dlib/test/global_optimization.cpp

@@ -160,29 +160,29 @@ namespace
         print_spinner();
         auto rosen = [](const matrix<double,0,1>& x) { return -1*( 100*std::pow(x(1) - x(0)*x(0),2.0) + std::pow(1 - x(0),2)); };
 
-        auto result = find_max_global(rosen, {0, 0}, {2, 2}, max_function_calls(100), 0);
+        auto result = find_max_global(rosen, {0.1, 0.1}, {2, 2}, max_function_calls(100), 0);
         matrix<double,0,1> true_x = {1,1};
 
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(max(abs(true_x-result.x)) < 1e-5, max(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_max_global(rosen, {0, 0}, {2, 2}, max_function_calls(100));
+        result = find_max_global(rosen, {0.1, 0.1}, {2, 2}, max_function_calls(100));
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(max(abs(true_x-result.x)) < 1e-5, max(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_max_global(rosen, {0, 0}, {2, 2}, std::chrono::seconds(5));
+        result = find_max_global(rosen, {0.1, 0.1}, {2, 2}, std::chrono::seconds(5));
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(max(abs(true_x-result.x)) < 1e-5, max(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_max_global(rosen, {0, 0}, {2, 2}, {false,false}, max_function_calls(100));
+        result = find_max_global(rosen, {0.1, 0.1}, {2, 2}, {false,false}, max_function_calls(100));
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(max(abs(true_x-result.x)) < 1e-5, max(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_max_global(rosen, {0, 0}, {0.9, 0.9}, {false,false}, max_function_calls(100));
+        result = find_max_global(rosen, {0.1, 0.1}, {0.9, 0.9}, {false,false}, max_function_calls(140));
         true_x = {0.9, 0.81};
         dlog << LINFO << "rosen, bounded at 0.9: " <<  trans(result.x);
         DLIB_TEST_MSG(max(abs(true_x-result.x)) < 1e-5, max(abs(true_x-result.x)));
@@ -221,24 +221,24 @@ namespace
         print_spinner();
         auto rosen = [](const matrix<double,0,1>& x) { return +1*( 100*std::pow(x(1) - x(0)*x(0),2.0) + std::pow(1 - x(0),2)); };
 
-        auto result = find_min_global(rosen, {0, 0}, {2, 2}, max_function_calls(100), 0);
+        auto result = find_min_global(rosen, {0.1, 0.1}, {2, 2}, max_function_calls(100), 0);
         matrix<double,0,1> true_x = {1,1};
 
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(min(abs(true_x-result.x)) < 1e-5, min(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_min_global(rosen, {0, 0}, {2, 2}, max_function_calls(100));
+        result = find_min_global(rosen, {0.1, 0.1}, {2, 2}, max_function_calls(100));
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(min(abs(true_x-result.x)) < 1e-5, min(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_min_global(rosen, {0, 0}, {2, 2}, std::chrono::seconds(5));
+        result = find_min_global(rosen, {0.1, 0.1}, {2, 2}, std::chrono::seconds(5));
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(min(abs(true_x-result.x)) < 1e-5, min(abs(true_x-result.x)));
         print_spinner();
 
-        result = find_min_global(rosen, {0, 0}, {2, 2}, {false,false}, max_function_calls(100));
+        result = find_min_global(rosen, {0.1, 0.1}, {2, 2}, {false,false}, max_function_calls(100));
         dlog << LINFO << "rosen: " <<  trans(result.x);
         DLIB_TEST_MSG(min(abs(true_x-result.x)) < 1e-5, min(abs(true_x-result.x)));
         print_spinner();