//+------------------------------------------------------------------+
//|                                                          SMA.mq5 |
//|                        Copyright 2009, MetaQuotes Software Corp. |
//|                                              http://www.mql5.com |
//+------------------------------------------------------------------+
#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1
#property indicator_type1   DRAW_LINE
#property indicator_color1  Red

input int MAPeriod= 13;
input int MAShift = 0;

double ExtLineBuffer[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+  
void OnInit()
  {
   SetIndexBuffer(0,ExtLineBuffer,INDICATOR_DATA);
   PlotIndexSetInteger(0,PLOT_SHIFT,MAShift);
   PlotIndexSetInteger(0,PLOT_DRAW_BEGIN,MAPeriod);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,const int prev_calculated,const int begin,const double &price[])
  {
   if(rates_total<MAPeriod-1)
      return(0);

   int first,bar,iii;
   double Sum,SMA;

   if(prev_calculated==0)
      first=MAPeriod-1+begin;
   else first=prev_calculated-1;

   for(bar=first;bar<rates_total;bar++)
     {
      Sum=0.0;
      for(iii=0;iii<MAPeriod;iii++)
         Sum+=price[bar-iii];

      SMA=Sum/MAPeriod;

      ExtLineBuffer[bar]=SMA;
     }

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