Add \directsumthree to mjo-common.

diff --git a/mjo-common.tex b/mjo-common.tex
index 5c0162a76b575e8336bad47740cdeec47f90d1c7..fe4ee5264facee2fd54dd657ed107ead679d2195 100644 (file)
--- a/mjo-common.tex
+++ b/mjo-common.tex
@@ -38,6 +38,9 @@
 % The direct sum of two things.
 \providecommand*{\directsum}[2]{ {#1}\oplus{#2} }
 
+% The direct sum of three things.
+\providecommand*{\directsumthree}[3]{ \directsum{#1}{\directsum{#2}{#3}} }
+
 % The factorial operator.
 \providecommand*{\factorial}[1]{ {#1}! }