SI

//+------------------------------------------------------------------+
//|                                                           SI.mq4 |
//|                                                             Raff |
//|                                                   raff1410@o2.pl |
//+------------------------------------------------------------------+
#property copyright "Raff"
#property link      "just_raff1410@yahoo.com"

#property indicator_separate_window
#property indicator_buffers 1
#property indicator_color1 Red

//---- input parameters
extern double    T           = 1;
extern int       CountBars   = 10000;

//---- buffers
double ASI[];

//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
//---- indicators
   IndicatorBuffers(1);
   SetIndexStyle(0,DRAW_LINE);
   SetIndexBuffer(0,ASI);

//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
  {
//----
   
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int start()
  {
   int    i, counted_bars=IndicatorCounted();
//----
   double pHigh, pLow, pOpen, pClose;
   double pHigh_1, pLow_1, pOpen_1, pClose_1;
   double K, R, R_1, R_2, R_3, R_4, X, SI ;

   if (CountBars>Bars) CountBars=Bars-10;
   i=CountBars-10;
   ASI[i+1]=0;
   while(i>=0)
   {
   pHigh    = High[i];
   pLow     = Low[i];
   pOpen    = Open[i];
   pClose   = Close[i];

   pHigh_1  = High[i+1];
   pLow_1   = Low[i+1];
   pOpen_1  = Open[i+1];
   pClose_1 = Close[i+1];
   
   R_1      = MathAbs(pHigh-pClose_1);
   R_2      = MathAbs(pLow-pClose_1);
   R_3      = MathAbs(pHigh-pLow);
   R_4      = MathAbs(pClose_1-pOpen_1);
   K        = MathMax(R_1,R_2);
  
   if (R_1>=MathMax(R_2,R_3))
   {
       R    = R_1 - R_2/2 + R_4/4;
   }
   else
   if (R_2>=MathMax(R_1,R_3))
   {
       R    = R_2 - R_1/2 + R_4/4;
   }
   else
   {
       R    = R_3 + R_4/4;
   }
   
   if (R==0) SI=0;
   else 
   {
       X    = (pClose_1-pClose)+(pClose_1-pOpen_1)/2+(pClose-pOpen)/4;
       SI   = 50 * (X/R) * (K/T);
   }

   ASI[i] = ASI[i+1]-SI;

   i--;
   }  

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