1 files changed, 1 insertions, 0 deletions
diff --git a/js/util.js b/js/util.js
index 7859b2b..cdabbe1 100644
--- a/js/util.js
+++ b/js/util.js
@@ -47,6 +47,7 @@ function rand(n){ return (Math.random()*n) }
 function randint(n){ return rand(n)|0 }
 function randrange(a,b){ return a + rand(b-a) }
 function randsign(){ return random() >= 0.5 ? -1 : 1 }
+function randnullsign(){ var r = random(); return r < 0.333 ? -1 : r < 0.666 ? 0 : 1 }
 
 function xrandom(exp){ return Math.pow(Math.random(), exp) }
 function xrand(exp,n){ return (xrandom(exp)*n) }