2 files changed, 3 insertions, 1 deletions
diff --git a/instructions.html b/instructions.html
index 39bf3bf..25f6e32 100644
--- a/instructions.html
+++ b/instructions.html
@@ -18,7 +18,8 @@ r, g, b, a = color values
 mousex, mousey
 
 <u>Math aliases</u>
-floor, ceil, round, abs, sign
+floor, ceil, round
+abs, sign, mod(n,m)
 pow, exp, sqrt
 cos, sin, tan
 acos, asin, atan, atan2
diff --git a/js/util.js b/js/util.js
index 024476e..bbf8674 100644
--- a/js/util.js
+++ b/js/util.js
@@ -41,6 +41,7 @@ function choice(a){ return a[randint(a.length)] }
 function deg(n){ return n*180/PI }
 function rad(n){ return n*PI/180 }
 function pixel(x,y){ return 4*(y*w+x) }
+function mod(n,m){ return n-(m * Math.floor(n/m)) }
 
 function step (n,a,b) {
   return clamp((n - a) / (b - a), 0.0, 1.0);