Henderson's filter

[Arthur Singer]

Hallo,

ich habe den Henderson Filter in MQL4 entwickelt, aber es gibt das Problem, dass es am Ende anscheinend Fehlberechnungen gibt. Ich habe lange Zeit gesucht und den Fehler nicht gefunden.

//+------------------------------------------------------------------+
//|                                           Henderson's filter.mq4 |
//|                                        Copyright 2018, Arthur S. |
//|                    https://www.mql5.com/de/users/michael12345678 |
//+------------------------------------------------------------------+
#property copyright "Copyright 2018, Arthur S."
#property link      "https://www.mql5.com/de/users/michael12345678"
#property version   "1.00"
#property strict

#property indicator_chart_window
#property indicator_buffers 2
#property indicator_plots   1
#property indicator_label1  "Henderson's filter"
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrCrimson
#property indicator_width1  2

input int                inpPeriod = 32;          // Period
input ENUM_APPLIED_PRICE inpPrice  = PRICE_CLOSE; // Price

double val[],prices[],weights[];
int _filterSize,_half,_size;
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
{
   SetIndexBuffer(0,val,INDICATOR_DATA); 
   SetIndexBuffer(1,prices,INDICATOR_CALCULATIONS); 
   //
   //---
   //
      _filterSize = MathMax(inpPeriod,3);
         if (MathMod(_filterSize,2)==0) _filterSize++; ArrayResize(weights,_filterSize);
         double m = MathFloor(_filterSize/2.0); _half = (int)m;
         double divisor = 8.0*(m+2.0)*((m+2.0)*(m+2.0)-1.0)*(4.0*(m+2.0)*(m+2)-1.0)*(4.0*(m+2.0)*(m+2.0)-9.0)*(4.0*(m+2.0)*(m+2.0)-25.0);  
         for (int j=-_half; j<=_half; j++)
            weights[j+_half] = 315.0*((m+1.0)*(m+1.0)-(j*j))*((m+2.0)*(m+2.0)-(j*j))*((m+3.0)*(m+3.0)-(j*j))*(3.0*(m+2.0)*(m+2.0)-11.0*(j*j)-16.0)/divisor;
            _size = ArraySize(weights);
   //
   //---            
   //
   IndicatorSetString(INDICATOR_SHORTNAME,"Henderson's filter ("+string(inpPeriod)+")");
   
   return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
{
   if(Bars(_Symbol,_Period)<rates_total) return(-1);
   for (int i=(int)MathMax(prev_calculated-_half,0); i<rates_total; i++)
   {
      double mod = 1.0;
      if ((rates_total-i-1)<_half)
      {
         double weightTotal = 0; for (int k=_half-(rates_total-i-1); k<_size; k++) weightTotal += weights[k]; mod = 1.0/weightTotal;               
      }
      //
      //---
      //
      double sum = mod*weights[_half]*getPrice(inpPrice,open,close,high,low,i,rates_total);
      for(int j=1; j<=_half; j++)
      {
         if (i-j>=0         ) sum += mod*weights[_half+j]*getPrice(inpPrice,open,close,high,low,i-j,rates_total);
         if (i+j<rates_total) sum += mod*weights[_half-j]*getPrice(inpPrice,open,close,high,low,i+j,rates_total);
      }
      val[i] = sum;
   }    
   
   return(rates_total);
}
//+------------------------------------------------------------------+
double getPrice(ENUM_APPLIED_PRICE tprice,const double &open[],const double &close[],const double &high[],const double &low[],int i,int _bars)
  {
   if(i>=0)
      switch(tprice)
        {
         case PRICE_CLOSE:     return(close[i]);
         case PRICE_OPEN:      return(open[i]);
         case PRICE_HIGH:      return(high[i]);
         case PRICE_LOW:       return(low[i]);
         case PRICE_MEDIAN:    return((high[i]+low[i])/2.0);
         case PRICE_TYPICAL:   return((high[i]+low[i]+close[i])/3.0);
         case PRICE_WEIGHTED:  return((high[i]+low[i]+close[i]+close[i])/4.0);
        }
   return(0);
  }

[Carl Schreiber]

Du hast ein Problem mit den Indices der letzten Bars  0,1 .., rates_total-1 in MQL5 bzw rates_total-1, .. 1,0 in Mql4. Mir scheint Du musst da etwas umdrehen.

So entstehen wohl Wert gleich oder nahe Null so dass (Division durch Null) einmal unendlich oder etwas viel zu Großes und einmal Null im Indikatorpuffer steht.

Ich würde den Debugger verwenden - solange die Märkte noch zu sind - und ihn für die letzten 33 starten => if (time[i]>D'2018.09.28 23:40') DebugBreak();

BTW, ich würde in mql4 den Index der Bars von rates_total bis 0 laufen lassen, denn eigentlich ist bar #0 die aktuelle (in mql4) - check mal time[i] im Debugger!

Hast Du das bedacht:

PS: be aware that Henderson's filters are from a family of centered smoothers, i.e. they recalculate half period bars. (von https://www.mql5.com/en/code/21605)