Add a \factorial command.

diff --git a/mjo-common.tex b/mjo-common.tex
index e19d7883e6d9a7c70a5865d314cc9dabf1762f46..408ca3310e7dbff8e498936e4bfefbe77e49c483 100644 (file)
--- a/mjo-common.tex
+++ b/mjo-common.tex
@@ -29,6 +29,9 @@
 % The Cartesian product of three things.
 \providecommand*{\cartprodthree}[3]{ \cartprod{{#1}}{\cartprod{{#2}}{{#3}}} }
 
+% The factorial operator.
+\providecommand*{\factorial}[1]{ {#1}! }
+
 %
 % Product spaces
 %