Instantaneous Trend Line bands

ÿþ//------------------------------------------------------------------

#property copyright "© mladen, 2018"

#property link      "mladenfx@gmail.com"

//------------------------------------------------------------------

#property indicator_chart_window

#property indicator_buffers 6

#property indicator_plots   3

#property indicator_label1  "Filling"

#property indicator_type1   DRAW_FILLING

#property indicator_color1  clrDeepPink,clrLimeGreen

#property indicator_label2  "Instantaneous trend line"

#property indicator_type2   DRAW_LINE

#property indicator_color2  clrDarkGray

#property indicator_width2  2

#property indicator_label3  "Signal line"

#property indicator_type3   DRAW_LINE

#property indicator_color3  clrDarkGray

#property indicator_width3  1

//--- input parameters

input ENUM_APPLIED_PRICE inpPrice = PRICE_MEDIAN; // Price

input double             inpAlpha = 0.07;         // Alpha

//--- indicator buffers

double fillu[],filld[],itrend[],signal[],prices[],smooth[];

//+------------------------------------------------------------------+ 

//| Custom indicator initialization function                         | 

//+------------------------------------------------------------------+ 

int OnInit()

{

//--- indicator buffers mapping

   SetIndexBuffer(0,fillu  ,INDICATOR_DATA);

   SetIndexBuffer(1,filld  ,INDICATOR_DATA);

   SetIndexBuffer(2,itrend ,INDICATOR_DATA); 

   SetIndexBuffer(3,signal ,INDICATOR_DATA); 

   SetIndexBuffer(4,prices ,INDICATOR_CALCULATIONS); 

   SetIndexBuffer(5,smooth ,INDICATOR_CALCULATIONS); 

//--- indicator short name assignment

   IndicatorSetString(INDICATOR_SHORTNAME,"Instantaneous trend line ("+(string)inpAlpha+")");

//---

   return (INIT_SUCCEEDED);

  }

//+------------------------------------------------------------------+

//| Custom indicator de-initialization function                      |

//+------------------------------------------------------------------+

void OnDeinit(const int reason)

  {

  }

//+------------------------------------------------------------------+

//| 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(prev_calculated);



   for (int i=(int)MathMax(prev_calculated-1,0); i<rates_total && !IsStopped(); i++)

   {

      prices[i] = getPrice(inpPrice,open,close,high,low,i,rates_total);

      smooth[i] = (i>2) ? (prices[i] + 2*prices[i-1] + 2*prices[i-2] + prices[i-3])/6 : prices[i];    

      itrend[i] = (i>1) ? (inpAlpha-inpAlpha*inpAlpha/4)*smooth[i]+ 0.5*inpAlpha*inpAlpha*smooth[i-1] - (inpAlpha-0.75*inpAlpha*inpAlpha)*smooth[i-2] + 2*(1 - inpAlpha)*itrend[i-1] - (1-inpAlpha)*(1-inpAlpha)*itrend[i-2] : itrend[i];

      signal[i] = (i>1) ? 2*itrend[i]-itrend[i-2] : itrend[i];

      fillu[i]  = itrend[i];

      filld[i]  = signal[i];

   }

   return(rates_total);

}

//+------------------------------------------------------------------+

//| Custom functions                                                 |

//+------------------------------------------------------------------+

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);

  }

//+------------------------------------------------------------------+