// title: Kaprekar
// author: henklass
// description:
// Kaprekar
// Take any four-digit number except multiples of 1111. Sort the digits. Make numbers of the digits in ascending and in descending order. Repeat with the difference. After no more than 7 steps you will reach 6174, Kaprekar's Constant. 
// This makes for some fine music, lasting about 13 hours.
// code:
/*
Kaprekar
Take any four-digit number except multiples of 1111. Sort the digits. Make numbers of the digits in ascending and in descending order. Repeat with the difference. After no more than 7 steps you will reach 6174, Kaprekar's Constant. 
If you use three-digit numbers, you will get 495 in no more than 6 steps.
*/
s.boot;

(
//Synthdefs: sinewaves for numbers, with pan
SynthDef( \numbers, {|freq=30, panpos|
		Out.ar(0,
			Pan2.ar(SinOsc.ar(freq, mul: 0.5*EnvGen.kr(Env.linen(0.01, 0.1, 0.01, 0.6), doneAction: 2)),panpos)
		)
}).add;
//sawtooth for digits, filter associated with number of repetitions
SynthDef( \digitsplayer, {|freq=30, cutoff|
		Out.ar(0,
			Pan2.ar(LPF.ar(Saw.ar(freq, mul: 0.5*EnvGen.kr(Env.perc(0.01,0.75), doneAction: 2)), cutoff),0)
		)
}).add;
)

(

var number, theNumber, greatest, smallest;
var digits=Array.newClear(4);


{
g=0; //greatest number of repetitions
for (1, 9998, { arg i;
	if ( i.mod(1111)!= 0, {
		number = i;
		number.postln;
		theNumber=number; //theNumber is used to be able to mess with the value while retaining the value of number
		if (theNumber < 150, {theNumber = theNumber + 150});
		o=Synth( \numbers, [freq: theNumber/5, panpos: 0]);
		0.1.wait;
		a=0; //number of repetitions
		while ( {number != 6174}, {
			digits.put(0, number.mod(10)); //isolate digits
			number=number.div(10);
			digits.put(1, number.mod(10));
			number=number.div(10);
			digits.put(2, number.mod(10));
			number=number.div(10);
			digits.put(3, number.mod(10));
			digits.sort; //sort digits
			//digits.postln;
			greatest=(1000*digits[3])+(100*digits[2])+(10 * digits[1]) + digits[0];
			greatest.post; " ".post;
			
			smallest=digits[3] + (10*digits[2])+(100*digits[1])+(1000*digits[0]);
			smallest.post; " ".post;
			//(digits.mirror2+60).postln;
			
			//play the digits
			Pbind(
			\instrument, \digitsplayer,
			\freq, Pseq(digits.mirror2+60).midicps,
			\cutoff, 500*(a+1),
			\dur, 0.1
			).play;
			0.8.wait;
		
			//play greatest and smallest
			
			if (smallest < 150, {smallest = smallest + 150;
										greatest = greatest + 150});
			o=Synth( \numbers, [freq: smallest/5, panpos: -1]);
			p=Synth( \numbers, [freq: greatest/5, panpos: 1]);
			0.1.wait;
			
			number=greatest-smallest;

			theNumber=number;
			if (theNumber < 150, {theNumber = theNumber + 150});
			o=Synth( \numbers, [freq: theNumber/5, panpos: 0]);
			number.postln;
			0.1.wait;
			a=a+1;
		});
		a.postln;
		if (a>g, {g=a});
	});
});
g.postln;
}.fork;
)