Ehlers Super Smoother Smoothed oscillator

//+------------------------------------------------------------------+
//|                                                  Accelerator.mq4 |
//|                      Copyright © 2005, MetaQuotes Software Corp. |
//|                                       http://www.metaquotes.net/ |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2009, Julien Loutre"
#property link      "http://www.zenhop.com"

#property  indicator_separate_window
#property  indicator_buffers 3
#property  indicator_color1  LightBlue
#property  indicator_color2  DodgerBlue
#property  indicator_color3  Red

extern int        CuttOff  = 15;
extern double     alpha    = 0.15;
extern int        shift    = 0;

double      EMA[],Osc[],OscUP[],OscDOWN[];


int init() {
   IndicatorBuffers(3);
   SetIndexStyle(0,DRAW_LINE);
   SetIndexStyle(1,DRAW_HISTOGRAM,0,2);
   SetIndexStyle(2,DRAW_HISTOGRAM,0,2);
   IndicatorDigits(6);
   SetIndexDrawBegin(0,0);
   SetIndexBuffer(0,EMA);
   SetIndexBuffer(1,OscUP);
   SetIndexBuffer(2,OscDOWN);
   SetIndexShift(0,shift);
   SetIndexLabel(0,NULL);
   SetIndexLabel(0,"Osc");
   SetIndexLabel(1,"Osc UP");
   SetIndexLabel(2,"Osc DOWN");
   IndicatorShortName("Two pole Smoothed Oscillator ("+CuttOff+","+DoubleToStr(alpha,2)+")");
   
   return(0);
}
  
int start() {
   int    counted_bars=IndicatorCounted();
   int    limit,i;
   
   if(counted_bars>0) counted_bars--;
   limit=Bars-counted_bars;
   
   for(i=limit-1; i>=0; i--) {
      EMA[i] = (alpha-((alpha/2)*(alpha/2)))*getValue(i)+((alpha*alpha)/2)*getValue(i+1)-(alpha-(3*(alpha*alpha)/4))*getValue(i+2)+2*(1-alpha)*EMA[i+1]-((1-alpha)*(1-alpha))*EMA[i+2];
      
      if (EMA[i] > EMA[i+1]) {
         OscUP[i] = EMA[i];
         OscDOWN[i] = EMPTY_VALUE;
      }
      if (EMA[i] < EMA[i+1]) {
         OscUP[i] = EMPTY_VALUE;
         OscDOWN[i] = EMA[i];
      }
   }
   return(0);
}

double getValue(int i) {
   return(iCustom(NULL,0,"Ehlers Two Pole Super Smoother Filter", CuttOff, 0, i)-iCustom(NULL,0,"Ehlers Two Pole Super Smoother Filter", CuttOff, 0, i+1));
}