From 1948b232ae16b7f8ff7036bafc7cfcd9a7a5749c Mon Sep 17 00:00:00 2001
From: Antti H S Laaksonen <ahslaaks@cs.helsinki.fi>
Date: Wed, 22 Feb 2017 21:37:10 +0200
Subject: [PATCH] Add difference array to index

---
 chapter09.tex | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/chapter09.tex b/chapter09.tex
index fd2948f..572e6aa 100644
--- a/chapter09.tex
+++ b/chapter09.tex
@@ -1314,6 +1314,8 @@ retrieve single values.
 We focus on an operation that increases all
 elements in a range $[a,b]$ by $x$.
 
+\index{difference array}
+
 Surprisingly, we can use the data structures
 presented in this chapter also in this situation.
 To do this, we build a \key{difference array}