diff --git a/preamble/math_macros_functions.tex b/preamble/math_macros_functions.tex
index 404b737..3c9a273 100644
--- a/preamble/math_macros_functions.tex
+++ b/preamble/math_macros_functions.tex
@@ -18,6 +18,8 @@
 \newcommand{\inprod}[2]{\tuple{#1, #2}}                                          % \inprod{v}{w}         inner product
 \newcommand{\powgroup}[1]{\tuple{#1}}                                            % \powgroup{arg}        image of f={g^n | n in Z}
 
+\newcommand{\Oh}[1]{\ensuremath{\mathcal{O}(#1)}}                                % \Oh{n}     = O(N)
+
 \newcommand{\dboxed}[1]{{%
 \tikz[baseline={([yshift=-1ex]current bounding box.center)}]
     \node [rectangle, minimum width=1ex, inner sep=.3ex, outer sep=.3ex, dashed, draw] {\normalcolor$\displaystyle#1$};}}