From b619a857188e9d08c66eae9173088fb62e06728f Mon Sep 17 00:00:00 2001
From: Johann Dreo <johann.dreo@thalesgroup.com>
Date: Thu, 6 Jun 2013 11:43:34 +0200
Subject: [PATCH] bugfix: do not allow null interval in hypervolume diff metric

---
 eo/src/utils/eoRealBounds.h                    |  2 +-
 .../metric/moeoHyperVolumeDifferenceMetric.h   | 18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/eo/src/utils/eoRealBounds.h b/eo/src/utils/eoRealBounds.h
index 9d046be1a..8d55d793a 100644
--- a/eo/src/utils/eoRealBounds.h
+++ b/eo/src/utils/eoRealBounds.h
@@ -234,7 +234,7 @@ public :
         assert( repRange >= 0 );
 #ifndef NDEBUG
         if( repRange == 0 ) {
-            eo::log << eo::warnings << "Null range in eoRealBounds (min=" << _min << ", max=" << _max << ")" << std::endl;
+            eo::log << eo::warnings << "Warning: null range in eoRealBounds (min=" << _min << ", max=" << _max << ")" << std::endl;
         }
 #endif
     }
diff --git a/moeo/src/metric/moeoHyperVolumeDifferenceMetric.h b/moeo/src/metric/moeoHyperVolumeDifferenceMetric.h
index 906923b98..533d29296 100644
--- a/moeo/src/metric/moeoHyperVolumeDifferenceMetric.h
+++ b/moeo/src/metric/moeoHyperVolumeDifferenceMetric.h
@@ -163,12 +163,26 @@ class moeoHyperVolumeDifferenceMetric : public moeoVectorVsVectorBinaryMetric <
                     min = std::min(min, _set2[j][i]);
                     max = std::max(max, _set2[j][i]);
                 }
-                bounds[i] = eoRealInterval(min, max);
+                if( min == max ) {
+                    bounds[i] = eoRealInterval(min-tiny(), max+tiny());
+                } else {
+                    bounds[i] = eoRealInterval(min, max);
+                }
             }
         }
     }
 
-  	private:
+    protected:
+
+    /**
+     * Returns a very small value that can be used to avoid extreme cases (where the min bound == the max bound)
+     */
+    static double tiny()
+    {
+      return 1e-6;
+    }
+
+    private:
 
     /*boolean indicates if data must be normalized or not*/
     bool normalize;