diff --git a/commands.tex b/commands.tex
index 30fb30e3..3b529ca3 100644
--- a/commands.tex
+++ b/commands.tex
@@ -1 +1,4 @@
 \newcommand{\eg}{\textit{e}.\textit{g}.}
+
+% absolute value
+\DeclarePairedDelimiter\abs{\lvert}{\rvert}%
diff --git a/report.tex b/report.tex
index 54df6a91..8f9ea6d5 100644
--- a/report.tex
+++ b/report.tex
@@ -26,6 +26,7 @@ headsepline,
 \usepackage[english]{babel}
 % math stuff
 \usepackage{amsmath}
+\usepackage{mathtools}
 
 % UTF-8 encoding
 \usepackage[utf8]{inputenc}