diff --git a/README.md b/README.md
index 48bca905..1f93aef0 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,8 @@ Util.draw(gens);
 // █   █  █   ████  █   █ ██ █ ██ █  █ █ ██
 ```
 
+## Scale tuning
+
 Use the `new TL.Scala()` class to import a *.scl* file (Scala tuning format) to work with custom tuning systems apart from the Western 12-TET (Equal Temperament) tuning or use one of the tunings from a database with over 5000 tunings from [Stichting Huygens-Fokker](http://www.huygens-fokker.org/scala/).
 
 ```js
@@ -74,6 +76,8 @@ scl.names;
 //   '08-19', ... and 5000 more]
 ```
 
+## Expand and stretch array
+
 Expand an array by analyzing its internal structure
 
 ```js 
diff --git a/docs/algorithmic-methods.md b/docs/algorithmic-methods.md
index 350f6b10..f9d93193 100644
--- a/docs/algorithmic-methods.md
+++ b/docs/algorithmic-methods.md
@@ -179,7 +179,7 @@ ca.rule(9);
 
 ```
 
-## collatz
+## collatz conjecture
 
 Generate an array of numbers from the Collatz Conjecture, also known as the `3n+1` conjecture. Start with any positive integer `n`. Each next number is obtained from the previous number as follows: If the previous number is even then the next term is the previous term divided by 2. If the previous term is odd tthen the next term is 3 times the prevous term plus 1. The conjecture is that no matter what value of `n`, the sequence will always reach one. The length of the output is quite unpredicatable and can therefore be an interesting sequence for algorithmic composition.
 
@@ -188,8 +188,28 @@ Generate an array of numbers from the Collatz Conjecture, also known as the `3n+
 
 ```js
 // the collatz sequence for the number 15
-Algo.collatz(15);
-//=> [] 
+Algo.collatz(7);
+//=> [
+//  1,  2,  4,  8, 16,  5,
+//  10, 20, 40, 13, 26, 52,
+//  17, 34, 11, 22
+//	]
+
+// return the collatz sequence with a modulus operation (default = 2)
+Algo.collatzMod(7, 12);
+//=> [
+//   1,  2,  4,  8, 4, 5,
+//  10,  8,  4,  1, 2, 4,
+//   5, 10, 11, 10
+//	] 
+
+// the collatz sequence can encounter quite big values
+// so alternatively you can use bigCollatz and bigCollatzMod
+// to allow for larger number calculations
+Algo.bigCollatz('931386509544713451').length;
+// => 2283
+
+Algo.bigCollatzMod('931386509544713451');
 ```
 
 ## fibonacci
diff --git a/src/gen-complex.js b/src/gen-complex.js
index 175d995e..25053494 100644
--- a/src/gen-complex.js
+++ b/src/gen-complex.js
@@ -157,12 +157,18 @@ function collatz(n=12){
 }
 exports.collatz = collatz;
 
-function collatzMod(n=12){
-	return Util.mod(collatz(n), 2);
+// Return the modulus of a collatz conjecture sequence
+// Set the modulo
+// 
+// @param {Int+} -> starting number
+// @param {Int+} -> modulus
+// 
+function collatzMod(n=12, m=2){
+	return Util.mod(collatz(n), Math.min(m, Math.floor(m)));
 }
 exports.collatzMod = collatzMod;
 
-// The collatz conjecture with BigNumber
+// The collatz conjecture with BigNumber library
 // 
 function bigCollatz(n){
 	let num = new BigNumber(n);
@@ -181,6 +187,19 @@ function bigCollatz(n){
 }
 exports.bigCollatz = bigCollatz;
 
+// Return the modulus of a collatz conjecture sequence
+// Set the modulo
+// 
+function bigCollatzMod(n=12, m=2){
+	let arr = bigCollatz(n);
+	for (let i in arr){
+		arr[i] = new BigNumber(arr[i]);
+		arr[i] = arr[i].mod(m).toNumber();
+	}
+	return arr;
+}
+exports.bigCollatzMod = bigCollatzMod;
+
 // Generate any n-bonacci sequence as an array of BigNumber objects
 // F(n) = t * F(n-1) + F(n-2). This possibly generatres various 
 // integer sequences: fibonacci, pell, tribonacci
diff --git a/test/serialism.test.js b/test/serialism.test.js
index b551ffb1..42516bc8 100644
--- a/test/serialism.test.js
+++ b/test/serialism.test.js
@@ -55,12 +55,14 @@ console.log();
 
 fullTest();
 
+// console.log(Algo.bigCollatzMod(100000));
+
 function fullTest(){
 	console.time('Total Time');
 
 	// testSerial();
 	// testGen();
-	testAlgo();
+	// testAlgo();
 	// testRand();
 	// testMod();
 	// testStat();
@@ -190,8 +192,8 @@ function testAlgo(){
 	
 	test('Algo.collatzMod()');
 	test('Algo.collatzMod(43)');
-	test('Algo.collatzMod(7)');
-	test('Algo.collatzMod(314)');
+	test('Algo.collatzMod(7, 12)');
+	test('Algo.collatzMod(314, 5)');
 
 	pagebreak("Fibonacci");
 	test('Algo.fibonacci()');