//+------------------------------------------------------------------+
//|                                   TestScalingLambdaMaxSymbol.mq5 |
//|                             Copyright 2000-2026, MetaQuotes Ltd. |
//|                                              http://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2000-2026, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property script_show_inputs
//--- input parameters
input string WorkSymbol   = "EURUSD";     // Symbol
input int    YearStart    = 2024;
input int    YearEnd      = 2025;
#include <Graphics\Graphic.mqh>
//+------------------------------------------------------------------+
//| GetHistoricalData                                                |
//+------------------------------------------------------------------+
bool GetHistoricalData(double &data[], string symbol, ENUM_TIMEFRAMES tf, int year_start, int year_end)
  {
   datetime from = StringToTime(IntegerToString(year_start) + ".01.01 00:00");
   datetime to   = StringToTime(IntegerToString(year_end)   + ".12.31 23:59");
   int copied = CopyClose(symbol, tf, from, to, data);
   if(copied <= 0)
     {
      Print("Error in CopyClose: ", GetLastError());
      ArrayResize(data, 0);
      return false;
     }
//PrintFormat("Loaded bars: %d (%s %s)", ArraySize(data), symbol, EnumToString(tf));
   return true;
  }
//+------------------------------------------------------------------+
//| LinearRegression                                                 |
//+------------------------------------------------------------------+
void LinearRegression(const double &x[], const double &y[], int n, double &a, double &b)
  {
   double sx = 0, sy = 0, sxx = 0, sxy = 0;
   for(int i = 0; i < n; i++)
     {
      sx  += x[i];
      sy  += y[i];
      sxx += x[i] * x[i];
      sxy += x[i] * y[i];
     }
   double denom = n * sxx - sx * sx;
   a = (n * sxy - sx * sy) / denom;
   b = (sy - a * sx) / n;
  }
//+------------------------------------------------------------------+
//| Scaling test for one timeframe                                   |
//+------------------------------------------------------------------+
bool TestScalingLambaMaxTF(string symbol, ENUM_TIMEFRAMES tf, double &logT_out[], double &logLambda_out[], double &alpha_out)
  {
   MathSrand(42);
   double prices[];
   if(!GetHistoricalData(prices, symbol, tf, YearStart, YearEnd))
      return false;
   int Tvals[];
   int nT=8;
   int T0=64;
   ArrayResize(Tvals, nT);
   for(int i = 0; i < nT; i++)
      Tvals[i] = T0 << i;
   ArrayResize(logT_out, nT);
   ArrayResize(logLambda_out, nT);
   int data_size = ArraySize(prices);
   vector<double> data_prices;
   for(int i = 0; i < nT; i++)
     {
      int T = Tvals[i];
      int MC = 1000;
      double lambda_sum = 0.0;
      for(int k = 0; k < MC; k++)
        {
         if(data_size < T)
            break;
         int start = MathRand() % (data_size - T);
         data_prices.Resize(T);
         for(int j=0; j<T;  j++)
            data_prices[j]=prices[start+j];
         lambda_sum += data_prices.L1TrendFilterLambdaMax();
        }
      double lambda_avg = lambda_sum / MC;
      logT_out[i]      = MathLog((double)T);
      logLambda_out[i] = MathLog(lambda_avg);
      //PrintFormat("TF=%s T=%5d   <lambda_max>=%.6f", EnumToString(tf), T, lambda_avg);
     }
   double c;
   LinearRegression(logT_out, logLambda_out, nT, alpha_out, c);
   PrintFormat("%s (%s) estimated scaling exponent = %.4f", symbol,EnumToString(tf), alpha_out);
   return true;
  }
//+------------------------------------------------------------------+
//| TestScalingLambdaMaxSymbol                                       |
//+------------------------------------------------------------------+
void TestScalingLambdaMaxSymbol(string symbol)
  {
   ENUM_TIMEFRAMES timeframes[] = {PERIOD_M1, PERIOD_M2, PERIOD_M3, PERIOD_M4, PERIOD_M5, PERIOD_M6,
                                   PERIOD_M10, PERIOD_M12, PERIOD_M15, PERIOD_M20, PERIOD_M30, PERIOD_H1
                                  };
   uint colors[] = {clrRed,clrBlue,clrGreen,clrOrange,clrPurple,clrDarkGreen,clrCyan,
                    clrNavy,clrOrangeRed,clrDodgerBlue,clrCrimson,clrDarkRed
                   };
//---
   CGraphic g;
   g.Create(0, "ScalingLawTest", 0, 0, 0, 1000, 600);
   g.BackgroundMain("Scaling law of lambda_max (" + symbol + ")");
   g.BackgroundMainSize(16);
   PrintFormat("%s scaling test for standard timeframes",symbol);
   for(int i = 0; i < ArraySize(timeframes); i++)
     {
      double logT[], logLambda[], alpha;
      // Print("processing timeframe: ", EnumToString(timeframes[i]), " -----");
      if(TestScalingLambaMaxTF(symbol, timeframes[i], logT, logLambda, alpha))
        {
         g.CurveAdd(logT, logLambda, ColorToARGB(colors[i % ArraySize(colors)],255), CURVE_POINTS_AND_LINES, EnumToString(timeframes[i]));
        }
     }
   g.CurvePlotAll();
   g.Update();
//---
   DebugBreak();
  }
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
//--- estimate lambda_max scale exponent for price data
   TestScalingLambdaMaxSymbol(WorkSymbol);
  }
//+------------------------------------------------------------------+