Fixed a bug in find_max_factor_graph_viterbi() which sometimes

occurred when the model order was larger than the number of variables.

dlib/optimization/find_max_factor_graph_viterbi.h

@@ -18,7 +18,7 @@ namespace dlib
     {
         struct viterbi_data
         {
-            viterbi_data() :val(0), back_index(0) {}
+            viterbi_data() :val(-std::numeric_limits<double>::infinity()), back_index(0) {}
             double val;
             unsigned long back_index;
         };

dlib/test/find_max_factor_graph_viterbi.cpp

@@ -187,8 +187,17 @@ namespace
             do_test<0,3,8>();
             do_test<4,3,1>();
             do_test<4,3,0>();
-            do_test<0,3,0>();
 
+            do_test<3,2,1>();
+            do_test<3,2,0>();
+            do_test<3,2,2>();
+            do_test<2,2,1>();
+            do_test_negative<3,2,1>();
+            do_test_negative<3,2,0>();
+            do_test_negative<3,2,2>();
+            do_test_negative<2,2,1>();
+
+            do_test<0,3,0>();
             do_test<1,2,8>();
             do_test<2,2,7>();
             do_test<3,2,8>();