diff --git a/lib/extramath.js b/lib/extramath.js
index f0350cd..5c70090 100644
--- a/lib/extramath.js
+++ b/lib/extramath.js
@@ -43,6 +43,17 @@ function cos(A, B) {
     return similarity;
 }
 
+// Cartesian product: https://en.wikipedia.org/wiki/Cartesian_product
+function cartesianProduct(arr) {
+    return arr.reduce(function(a,b){
+        return a.map(function(x){
+            return b.map(function(y){
+                return x.concat([y]);
+            })
+        }).reduce(function(a,b){ return a.concat(b) },[])
+    }, [[]])
+}
+
 exports.DTM = DTM;
 exports.cos = cos;
 exports.measureSimilarity = function(s1, s2) {
@@ -52,8 +63,9 @@ exports.measureSimilarity = function(s1, s2) {
     var mat = dtm.toArray();
     return cos(mat[0], mat[1]);
 };
+exports.cartesianProduct = cartesianProduct;
 
-exports.VERSIONINFO = "ExtraMath module (extramath.js) version 0.0.3";
+exports.VERSIONINFO = "ExtraMath module (extramath.js) version 0.0.4";
 exports.AUTHOR = "catswords@protonmail.com";
 exports.global = global;
 exports.require = global.require;