Instant Trendline Filter

//+------------------------------------------------------------------+
//|                                    Instantaneous Trendline Filter|
//|                         Copyright © 2006, Luis Guilherme Damiani |
//|                                      http://www.damianifx.com.br |
//|
//+------------------------------------------------------------------+
#property copyright "Copyright © 2006, Luis Guilherme Damiani"
#property link      "http://www.damianifx.com.br"

#property indicator_buffers 2
//#property indicator_separate_window
#property indicator_chart_window

#property indicator_color1 Lime
#property indicator_color2 Red
//#property indicator_color3 Yellow

//---- input parameters
extern double       alpha=0.07;
extern int       maxbars=2000;
extern string 
Price_Choice="-----  Typical or Median  --------------";
extern bool is_median=true;

//---- buffers
double ind1[];
double ind2[];
//double AuxBuffer[];

//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
//---- indicators
   SetIndexStyle(0,DRAW_LINE);
   SetIndexBuffer(0,ind1);
   SetIndexStyle(1,DRAW_LINE);
   SetIndexBuffer(1,ind2);
 //  SetIndexStyle(2,DRAW_LINE);
//   SetIndexBuffer(2,AuxBuffer);
//   SetLevelValue(0,0.8);
//   SetLevelValue(1,-0.8);
//   ArrayInitialize(ind1,0);
//   ArrayInitialize(ind2,0);
//   ArrayInitialize(AuxBuffer,0);
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custor indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
{
//---- 
   
//----
   return(0);
}
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+

int start()
  {
      double pr0,pr1,pr2=0;
      
      int    counted_bars=IndicatorCounted();
      
      //double Normalized=0;
      //double Fish=0;
      //---- check for possible errors
      if(counted_bars<0) return(-1);
      int limit=Bars-counted_bars;
      if(limit>maxbars)limit=maxbars;      
      //if (limit>Bars-1)limit=Bars-1;   
      //---- 
      for (int i = limit; i>=0;i--)
      {
         if(is_median)
         {
            pr0=(High[i]+Low[i])/2;
            pr1=(High[i+1]+Low[i+1])/2;
            pr2=(High[i+2]+Low[i+2])/2;      
         }
         else
         {
            pr0=(High[i]+Low[i]+Close[i])/3;
            pr1=(High[i+1]+Low[i+1]+Close[i+1])/3;
            pr2=(High[i+2]+Low[i+2]+Close[i+2])/3;      
         }
	      
	      ind1[i]=(alpha-MathPow(alpha/2,2))*pr0
	           +(MathPow(alpha,2)/2)*pr1
	           -(alpha-3*MathPow(alpha,2)/4)*pr2
	           + 2*(1-alpha)*ind1[i+1]
	           -MathPow(1-alpha,2)*ind1[i+2];
	      ind2[i]=2*ind1[i]-ind1[i+2];
         
       }
   
//----
   return(0);
  }
//+------------------------------------------------------------------+