fractal_dimension

//+------------------------------------------------------------------------------------------------------------------+
//|                                                                              fractal_dimension.mq4               |
//|                                                                              iliko [arcsin5@netscape.net]        |
//|                                                                                                                  |
//|                                                                                                                  |
//|  The Fractal Dimension Index determines the amount of market volatility. The easiest way to use this indicator is|
//|  to understand that a value of 1.5 suggests the market is acting in a completely random fashion.                 |
//|  As the market deviates from 1.5, the opportunity for earning profits is increased in proportion                 |
//|  to the amount of deviation.                                                                                     |
//|  But be carreful, the indicator does not show the direction of trends !!                                         |
//|                                                                                                                  |
//|  The indicator is RED when the market is in a trend. And it is blue when there is a high volatility.             |
//|  When the FDI changes its color from red to blue, it means that a trend is finishing, the market becomes         |
//|  erratic and a high volatility is present. Usually, these "blue times" do not go for a long time.They come before|
//|  a new trend.                                                                                                    |
//|                                                                                                                  |
//|  For more informations, see                                                                                      |
//|  http://www.forex-tsd.com/suggestions-trading-systems/6119-tasc-03-07-fractal-dimension-index.html               |
//|                                                                                                                  |
//|                                                                                                                  |   
//|  HOW TO USE INPUT PARAMETERS :                                                                                   |   
//|  -----------------------------                                                                                   |   
//|                                                                                                                  |   
//|      1) e_period [ integer >= 1 ]                                              =>  30                            |   
//|                                                                                                                  |   
//|         The indicator will compute the historical market volatility over this period.                            |   
//|         Choose its value according to the average of trend lengths.                                              |   
//|                                                                                                                  |   
//|      2) e_type_data [ int = {PRICE_CLOSE = 0,                                                                    |   
//|                              PRICE_OPEN  = 1,                                                                    |   
//|                              PRICE_HIGH  = 2,                                                                    |   
//|                              PRICE_LOW   = 3,                                                                    |   
//|                              PRICE_MEDIAN    (high+low)/2              = 4,                                      |   
//|                              PRICE_TYPICAL   (high+low+close)/3        = 5,                                      |   
//|                              PRICE_WEIGHTED  (high+low+close+close)/4  = 6}     => PRICE_CLOSE                   |   
//|                                                                                                                  |   
//|         Defines on which price type the Fractal Dimension is computed.                                           |   
//|                                                                                                                  |
//|      3) e_random_line [ 0.0 < double < 2.0 ]                                   => 1.5                            |
//|                                                                                                                  |
//|         Defines your separation betwen a trend market (red) and an erratic/high volatily one.                    |   
//|                                                                                                                  |   
//| v1.0 - February 2007                                                                                            |   
//+------------------------------------------------------------------------------------------------------------------+
#property link      "arcsin5@netscape.net"
//----
#property indicator_separate_window
#property indicator_levelcolor LimeGreen
#property indicator_levelwidth 1
#property indicator_levelstyle STYLE_DASH
#property indicator_buffers 2
#property indicator_color1 Blue
#property indicator_color2 Red
#property indicator_width1 2
#property indicator_width2 2
//************************************************************
// Input parameters
//************************************************************
extern int    e_period      =30;
extern int    e_type_data   =PRICE_CLOSE;
extern double e_random_line =1.5;
//************************************************************
// Constant
//************************************************************
string INDICATOR_NAME="FDI";
string FILENAME      ="___fractal_dimension.mq4";
double LOG_2;
//************************************************************
// Private vars
//************************************************************
//---- input buffer
double ExtInputBuffer[];
//---- output buffer
double ExtOutputBufferUp[];
double ExtOutputBufferDown[];
int g_period_minus_1;
//+-----------------------------------------------------------------------+
//| FUNCTION : init                                                       |                                                                                                                                                                                                                                                      
//| Initialization function                                               |                                   
//| Check the user input parameters and convert them in appropriate types.|                                                                                                    
//+-----------------------------------------------------------------------+
int init()
  {
   // Check e_period input parameter
   if(e_period < 2 )
     {
      Alert( "[ 10-ERROR  " + FILENAME + " ] input parameter \"e_period\" must be >= 1 (" + e_period + ")" );
      return( -1 );
     }
   if(e_type_data < PRICE_CLOSE || e_type_data > PRICE_WEIGHTED )
     {
      Alert( "[ 20-ERROR  " + FILENAME + " ] input parameter \"e_type_data\" unknown (" + e_type_data + ")" );
      return( -1 );
     }
   if(e_random_line < 0.0 || e_random_line > 2.0 )
     {
      Alert( "[ 30-ERROR  " + FILENAME + " ] input parameter \"e_random_line\" = " + e_random_line + " out of range ( 0.0 < e_random_line < 2.0 )" );
      return( -1 );
     }
   IndicatorBuffers( 3 );
   SetIndexBuffer( 0, ExtOutputBufferUp );
   SetIndexStyle( 0, DRAW_LINE, STYLE_SOLID, 2 );
   SetIndexBuffer( 1, ExtOutputBufferDown );
   SetIndexStyle( 1, DRAW_LINE, STYLE_SOLID, 2 );
   SetIndexBuffer( 2, ExtInputBuffer );
   SetLevelValue( 0, e_random_line );
   IndicatorShortName( INDICATOR_NAME );
   SetIndexLabel( 0, INDICATOR_NAME );
   SetIndexDrawBegin( 0, 2 * e_period );
   g_period_minus_1=e_period - 1;
   LOG_2=MathLog( 2.0 );
//----
   return( 0 );
  }
//+------------------------------------------------------------------+
//| FUNCTION : deinit                                                |
//| Custor indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
  {
   return(0);
  }
//+------------------------------------------------------------------+
//| FUNCTION : start                                                 |
//| This callback is fired by metatrader for each tick               |
//+------------------------------------------------------------------+
int start()
  {
   int countedBars=IndicatorCounted();
//---- check for possible errors
   if(countedBars < 0)
     {
      return(-1);
     }
   _computeLastNbBars( Bars - countedBars - 1 );
//----
   return( 0 );
  }
//+================================================================================================================+
//+=== FUNCTION : _computeLastNbBars                                                                            ===+
//+===                                                                                                          ===+
//+===                                                                                                          ===+
//+=== This callback is fired by metatrader for each tick                                                       ===+
//+===                                                                                                          ===+
//+=== In :                                                                                                     ===+
//+===    - lastBars : these "n" last bars must be repainted                                                    ===+
//+===                                                                                                          ===+
//+================================================================================================================+
//+------------------------------------------------------------------+
//| FUNCTION : _computeLastNbBars                                    |
//| This callback is fired by metatrader for each tick                |
//| In : - lastBars : these "n" last bars must be repainted           | 
//+------------------------------------------------------------------+
void _computeLastNbBars( int lastBars )
  {
   int pos;
   switch( e_type_data )
     {
      case PRICE_CLOSE    : _computeFdi( lastBars, Close ); break;
      case PRICE_OPEN     : _computeFdi( lastBars, Open ); break;
      case PRICE_HIGH     : _computeFdi( lastBars, High ); break;
      case PRICE_LOW      : _computeFdi( lastBars, Low ); break;
      case PRICE_MEDIAN   :
         for( pos=lastBars; pos>=0; pos--)ExtInputBuffer[pos]=(High[pos]+Low[pos])/2.0; _computeFdi( lastBars, ExtInputBuffer );
         break;
      case PRICE_TYPICAL  :
         for( pos=lastBars; pos>=0; pos--)ExtInputBuffer[pos]=(High[pos]+Low[pos]+Close[pos])/3.0; _computeFdi( lastBars, ExtInputBuffer );
         break;
      case PRICE_WEIGHTED :
         for( pos=lastBars; pos>=0; pos--)ExtInputBuffer[pos]=(High[pos]+Low[pos]+Close[pos]+Close[pos])/4.0; _computeFdi( lastBars, ExtInputBuffer );
         break;
      default :
         Alert( "[ 20-ERROR  " + FILENAME + " ] the imput parameter e_type_data <" + e_type_data + "> is unknown" );
     }
  }
//+------------------------------------------------------------------+
//| FUNCTION : _computeFdi                                           |
//| Compute FDI values from input data.                              |
//| In :                                                             |
//|    - lastBars : these "n" last bars must be repainted            |
//|    - inputData : data array on which the FDI will be applied     |
//+------------------------------------------------------------------+
void _computeFdi( int lastBars, double inputData[] )
  {
   int    pos, iteration;
   double diff, priorDiff;
   double length;
   double priceMax, priceMin;
   double fdi;
//----
   for( pos=lastBars; pos>=0; pos-- )
     {
      priceMax=_highest( e_period, pos, inputData );
      priceMin=_lowest( e_period, pos, inputData );
      length   =0.0;
      priorDiff=0.0;
//----
      for( iteration=0; iteration < g_period_minus_1; iteration++ )
        {
         if(( priceMax - priceMin)> 0.0 )
           {
            diff =(inputData[pos + iteration] - priceMin )/( priceMax - priceMin );
            if(iteration > 0 )
              {
               length+=MathSqrt( MathPow( diff - priorDiff, 2.0)+(1.0/MathPow( e_period, 2.0)) );
              }
            priorDiff=diff;
           }
        }
      if(length > 0.0 )
        {
         fdi=1.0 +(MathLog( length)+ LOG_2 )/MathLog( 2 * e_period );
        }
      else
        {
         /*
         ** The FDI algorithm suggests in this case a zero value.
         ** I prefer to use the previous FDI value.
         */
         fdi=0.0;
        }
      if(fdi > e_random_line )
        {
         ExtOutputBufferUp[pos]  =fdi;
         ExtOutputBufferUp[pos+1]=MathMin( ExtOutputBufferUp[pos+1], ExtOutputBufferDown[pos+1] );
         ExtOutputBufferDown[pos]=EMPTY_VALUE;
        }
      else
        {
         ExtOutputBufferDown[pos]  =fdi;
         ExtOutputBufferDown[pos+1]=MathMin( ExtOutputBufferUp[pos+1], ExtOutputBufferDown[pos+1] );
         ExtOutputBufferUp[pos]=EMPTY_VALUE;
        }
     }
  }
//+------------------------------------------------------------------+
//| FUNCTION : _highest                                              |
//| Search for the highest value in an array data                    |
//| In :                                                             |
//|    - n : find the highest on these n data                        |
//|    - pos : begin to search for from this index                   |
//|    - inputData : data array on which the searching for is done   |
//|                                                                  |
//| Return : the highest value                                       |                                                 |
//+------------------------------------------------------------------+
double _highest( int n, int pos, double inputData[] )
  {
   int length=pos + n;
   double highest=0.0;
//----
   for( int i=pos; i < length; i++ )
     {
      if(inputData[i] > highest)highest=inputData[i];
     }
   return( highest );
  }
//+------------------------------------------------------------------+
//| FUNCTION : _lowest                                               |                                                                                                          ===+
//| Search for the lowest value in an array data                     |
//| In :                                                             |
//|    - n : find the hihest on these n data                         |
//|    - pos : begin to search for from this index                   |
//|    - inputData : data array on which the searching for is done   |
//|                                                                  |
//| Return : the highest value                                       |
//+------------------------------------------------------------------+
double _lowest( int n, int pos, double inputData[] )
  {
   int length=pos + n;
   double lowest=9999999999.0;
//----
   for( int i=pos; i < length; i++ )
     {
      if(inputData[i] < lowest)lowest=inputData[i];
     }
   return( lowest );
  }
//+------------------------------------------------------------------+