//+------------------------------------------------------------------+
//|                                                   SuperTrend.mq4 |
//|                   Copyright © 2008, Jason Robinson (jnrtrading). |
//|                                   http://www.spreadtrade2win.com |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2008, Jason Robinson."
#property link      "http://www.spreadtrade2win.com"

#property indicator_chart_window
#property indicator_color1 Lime
#property indicator_color2 Red
#property indicator_width1 2
#property indicator_width2 2
#property indicator_buffers 2
double TrendUp[],TrendDown[];
int changeOfTrend;
extern int Nbr_Periods=10;
extern double Multiplier=3.0;
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
//---- indicators
   SetIndexBuffer(0,TrendUp);
   SetIndexStyle(0,DRAW_LINE,STYLE_SOLID,2);
   SetIndexLabel(0,"Trend Up");
   SetIndexBuffer(1,TrendDown);
   SetIndexStyle(1,DRAW_LINE,STYLE_SOLID,2);
   SetIndexLabel(1,"Trend Down");
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
  {
//----

//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int start()
  {
   int limit,i,flag,flagh,trend[];
   double up[],dn[],medianPrice,atr;

   int counted_bars=IndicatorCounted();
   if(counted_bars<0) return(-1);
   if(counted_bars>0) counted_bars--;
   limit=Bars-counted_bars;
   if(counted_bars==0) limit-=1+1;
//Print(limit);

   int xsize=ArraySize(TrendUp);
   ArrayResize(trend,xsize);
   ArrayResize(up,xsize);
   ArrayResize(dn,xsize);
//----
   for(i=limit; i>=0; i--) 
     {
      atr=iATR(NULL,0,Nbr_Periods,i);
      //Print("atr: "+atr[i]);
      medianPrice=(High[i]+Low[i])/2;
      //Print("medianPrice: "+medianPrice[i]);
      up[i]=medianPrice+(Multiplier*atr);
      //Print("up: "+up[i]);
      dn[i]=medianPrice-(Multiplier*atr);
      //Print("dn: "+dn[i]);
      trend[i]=1;

      if(Close[i]>up[i+1]) 
        {
         trend[i]=1;
         if(trend[i+1]==-1) changeOfTrend=1;
         //Print("trend: "+trend[i]);

        }
      else if(Close[i]<dn[i+1]) 
        {
         trend[i]=-1;
         if(trend[i+1]==1) changeOfTrend=1;
         //Print("trend: "+trend[i]);
        }
      else if(trend[i+1]==1) 
        {
         trend[i]=1;
         changeOfTrend=0;
        }
      else if(trend[i+1]==-1) 
        {
         trend[i]=-1;
         changeOfTrend=0;
        }

      if(trend[i]<0 && trend[i+1]>0) 
        {
         flag=1;
         //Print("flag: "+flag);
        }
      else 
        {
         flag=0;
         //Print("flagh: "+flag);
        }

      if(trend[i]>0 && trend[i+1]<0) 
        {
         flagh=1;
         //Print("flagh: "+flagh);
        }
      else 
        {
         flagh=0;
         //Print("flagh: "+flagh);
        }

      if(trend[i]>0 && dn[i]<dn[i+1])
         dn[i]=dn[i+1];

      if(trend[i]<0 && up[i]>up[i+1])
         up[i]=up[i+1];

      if(flag==1)
         up[i]=medianPrice+(Multiplier*atr);

      if(flagh==1)
         dn[i]=medianPrice-(Multiplier*atr);

      //-- Draw the indicator
      if(trend[i]==1) 
        {
         TrendUp[i]=dn[i];
         if(changeOfTrend==1) 
           {
            TrendUp[i+1] = TrendDown[i+1];
            changeOfTrend= 0;
           }
        }
      else if(trend[i]==-1) 
        {
         TrendDown[i]=up[i];
         if(changeOfTrend==1) 
           {
            TrendDown[i+1]= TrendUp[i+1];
            changeOfTrend = 0;
           }
        }
     }

//----
   return(0);
  }
//+------------------------------------------------------------------+