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CDifferencTwoSigmoidalMembershipFunction

Class for implementing the membership function in the form of a difference between two sigmoid functions with the А1, А2, С1 and С2 parameters.

Description

The function is based on a sigmoid curve. It allows creating membership functions with the values equal to 1 beginning with an argument value. Such functions are suitable if you need to set such linguistic terms as "short" or "long".

fuzzy_diffsigmoidal_function

A sample code for plotting a chart is displayed below.

Declaration

   class CDifferencTwoSigmoidalMembershipFuncion : public IMembershipFunction

Title

   #include <Math\Fuzzy\membershipfunction.mqh>

Inheritance hierarchy

  CObject

      IMembershipFunction

          CDifferencTwoSigmoidalMembershipFunction

Class methods

Class method

Description

A1

Gets and sets the first membership function slope ratio.

A2

Gets and sets the second membership function slope ratio.

С1

Gets and sets the first membership function inflection coordinate parameter.

С2

Gets and sets the second membership function inflection coordinate parameter.

GetValue

Calculates the value of the membership function by a specified argument.

Example

//+------------------------------------------------------------------+
//|                      DifferencTwoSigmoidalMembershipFunction.mq5 |
//|                        Copyright 2016, MetaQuotes Software Corp. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#include <Math\Fuzzy\membershipfunction.mqh>
#include <Graphics\Graphic.mqh>
//--- Create membership functions
CDifferencTwoSigmoidalMembershipFunction func1(5,1,8,7);
CDifferencTwoSigmoidalMembershipFunction func2(5,4,5,7);
CDifferencTwoSigmoidalMembershipFunction func3(5,6,2,7);
//--- Create wrappers for membership functions
double DifferencTwoSigmoidalMembershipFunction1(double x) { return(func1.GetValue(x)); }
double DifferencTwoSigmoidalMembershipFunction2(double x) { return(func2.GetValue(x)); }
double DifferencTwoSigmoidalMembershipFunction3(double x) { return(func3.GetValue(x)); }
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
//--- create graphic
   CGraphic graphic;
   if(!graphic.Create(0,"DifferencTwoSigmoidalMembershipFunction",0,30,30,780,380))
     {
      graphic.Attach(0,"DifferencTwoSigmoidalMembershipFunction");
     }
   graphic.HistoryNameWidth(70);
   graphic.BackgroundMain("DifferencTwoSigmoidalMembershipFunction");
   graphic.BackgroundMainSize(16);
//--- create curve
   graphic.CurveAdd(DifferencTwoSigmoidalMembershipFunction1,0.0,10.0,0.1,CURVE_LINES,"[5, 1, 8, 7]");
   graphic.CurveAdd(DifferencTwoSigmoidalMembershipFunction2,0.0,10.0,0.1,CURVE_LINES,"[5, 4, 5, 7]");
   graphic.CurveAdd(DifferencTwoSigmoidalMembershipFunction3,0.0,10.0,0.1,CURVE_LINES,"[5, 6, 2, 7]");
//--- sets the X-axis properties
   graphic.XAxis().AutoScale(false);
   graphic.XAxis().Min(0.0);
   graphic.XAxis().Max(10.0);
   graphic.XAxis().DefaultStep(1.0);
//--- sets the Y-axis properties
   graphic.YAxis().AutoScale(false);
   graphic.YAxis().Min(0.0);
   graphic.YAxis().Max(1.1);
   graphic.YAxis().DefaultStep(0.2);
//--- plot
   graphic.CurvePlotAll();
   graphic.Update();
  }


Updated: 2017.03.22