Reconcile interval differences between book + src

Author: hollasch

books/RayTracingInOneWeekend.html

@@ -1510,6 +1510,10 @@
 
         interval(double _min, double _max) : min(_min), max(_max) {}
 
+        double size() const {
+            return max - min;
+        }
+
         bool contains(double x) const {
             return min <= x && x <= max;
         }
@@ -1521,8 +1525,8 @@
         static const interval empty, universe;
     };
 
-    const static interval empty   (+infinity, -infinity);
-    const static interval universe(-infinity, +infinity);
+    const interval interval::empty    = interval(+infinity, -infinity);
+    const interval interval::universe = interval(-infinity, +infinity);
 
     #endif
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

src/InOneWeekend/interval.h

@@ -21,11 +21,6 @@ class interval {
         return max - min;
     }
 
-    interval expand(double delta) const {
-        auto padding = delta/2;
-        return interval(min - padding, max + padding);
-    }
-
     bool contains(double x) const {
         return min <= x && x <= max;
     }