Fixed bug in unit tests.

dlib/test/statistics.cpp

@@ -816,6 +816,7 @@ namespace
                 {
                     rs.add(rnd.get_random_gaussian() + 1);
                     tmp[i] += rs.mean();
+                    if (i > 0)
                         tmp_var[i] += rs.variance();
                 }
             }
@@ -845,10 +846,13 @@ namespace
                 {
                     rs.add(rnd.get_random_gaussian() + 1, rnd.get_random_gaussian() + 1);
                     tmp[i] += (rs.mean_y()+rs.mean_x())/2;
+                    if (i > 0)
+                    {
                         tmp_var[i] += (rs.variance_y()+rs.variance_x())/2;
                         tmp_covar[i] += rs.covariance();
                     }
                 }
+            }
 
             // should print all 1s basically since the mean and variance should always be 1.
             for (size_t i = 0; i < tmp.size(); ++i)