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  • #1

    Problem with EMA...

    Hi,

    I'm trying to write code for the Percent Price Oscillator...

    The algorithm for this code:

    Value1 = (EMA(Close, Length1) - EMA(Close, Length2)/EMA(Close, Length1); //PPO
    Value2 = EMA(Value1,Length); //Signal Line
    Value3 = (Value1 - Value2); //PPO-histogram
    Return (Value2, Value3);

    I have a problem with Value2... I don't know how to compute EMA on Value1...

    Could anyone help me?

    Thank you.
    Tags: None
  • #2
    Nooze
    You can use the efs attached to this post as a blueprint to calculate the EMA of Value1 of your script.
    Alex

    Comment

    • #3
      Alex, thank you very much for the link!

      I just recently switched from TradeStation to eSignal and do not enough experience programming EFS.... I really need this indicator because it is my primary indicator, but I can't write it myself...

      I have compiled the code, but it is not working in my eSignal.

      Here is example of my code:



      PHP Code:
      /************************************************
      Alexis C. Montenegro © August 2004                        
      Use and/or modify this code freely. If you redistribute it
      please include this and/or any other comment blocks and a 
      description of any changes you make.                      
      *****************************************************/

      var vMA1 = null;
      var       vMA2 = null;

      function       preMain() {

                setStudyTitle("PPO");
                setShowCursorLabel(false);
                setDefaultBarStyle(PS_SOLID, 0);
                setDefaultBarFgColor(Color.yellow, 0);
                setDefaultBarThickness(1, 0);
                setPlotType(PLOTTYPE_LINE, 0);
                //setPlotType(PLOTTYPE_HISTOGRAM); 
          //checkVersion(1,"http://share.esignal.com/ContentRoot/ACM%20Test/Formulas/basicMAx2.efs"); //Comment this line out if modifying the code
              
                var fp1 = new FunctionParameter("MALength", FunctionParameter.NUMBER);
                fp1.setLowerLimit(1);        
                fp1.setDefault(9);
          
          var       fp2 = new FunctionParameter("MAType", FunctionParameter.STRING);
                fp2.setName("MAType");
                fp2.addOption("MAStudy.SIMPLE");
                fp2.addOption("MAStudy.EXPONENTIAL");
                fp2.addOption("MAStudy.WEIGHTED");
                fp2.addOption("MAStudy.VOLUMEWEIGHTED");
                fp2.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default

                var fp3 = new FunctionParameter("MA1Length", FunctionParameter.NUMBER);
                fp3.setLowerLimit(1);        
                fp3.setDefault(12); //Edit this value to set a new default
          
                var fp4 = new FunctionParameter("MA1Source", FunctionParameter.STRING);
                fp4.setName("MA1Source");
                fp4.addOption("Close");
                fp4.addOption("High");
                fp4.addOption("Low");
                fp4.addOption("Open");
                fp4.addOption("HL/2");
                fp4.addOption("HLC/3");
                fp4.addOption("OHLC/4");
                fp4.setDefault("Close"); //Edit this value to set a new default     
          
                var fp5 = new FunctionParameter("MA1Type", FunctionParameter.STRING);
                fp5.setName("MA1Type");
                fp5.addOption("MAStudy.SIMPLE");
                fp5.addOption("MAStudy.EXPONENTIAL");
                fp5.addOption("MAStudy.WEIGHTED");
                fp5.addOption("MAStudy.VOLUMEWEIGHTED");
                fp5.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default
          
                var fp6 = new FunctionParameter("MA2Length", FunctionParameter.NUMBER);
                fp6.setLowerLimit(1);        
                fp6.setDefault(26); //Edit this value to set a new default
          
                var fp7 = new FunctionParameter("MA2Source", FunctionParameter.STRING);
                fp7.setName("MA1Source");
                fp7.addOption("Close");
                fp7.addOption("High");
                fp7.addOption("Low");
                fp7.addOption("Open");
                fp7.addOption("HL/2");
                fp7.addOption("HLC/3");
                fp7.addOption("OHLC/4");
                fp7.setDefault("Close"); //Edit this value to set a new default
          
                var fp8 = new FunctionParameter("MA2Type", FunctionParameter.STRING);
                fp8.setName("MA2Type");
                fp8.addOption("MAStudy.SIMPLE");
                fp8.addOption("MAStudy.EXPONENTIAL");
                fp8.addOption("MAStudy.WEIGHTED");
                fp8.addOption("MAStudy.VOLUMEWEIGHTED");
                fp8.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default
              
             
      }

      var       bPrimed = false; 
      var       vEMA = null;
      var       vEMA1 = null;   
      var       dPercent = 0.0;
      var       vValue = 0.0;
      var       aValue = null;
      var       vAvg = null;//used in the example provided

      function main(MALength,MAType,MA1Length,MA1Source,MA1Type,MA2Length,MA2Source,MA2Type) {

          var       i;
          var       vSum = 0.0;
          
                //insert below the calculations required for the user defined variable (example provided)
                if (vMA1 == null) vMA1 = new MAStudy(MA1Length, MA1Source, eval(MA1Type));
          if (      vMA2 == null) vMA2 = new MAStudy(MA2Length, MA2Source, eval(MA2Type));
                vAvg = ((vMA1-vMA2)/vMA1);/*((vMA1.getValue(MAStudy.MA)-vMA2.getValue(MAStudy.MA))/(vMA1.getValue(MAStudy.MA)));*/
          
          //end section for user defined variable

                vValue = vAvg; //replace vAvg with the user defined variable

                if(vValue == null) {
              return;
          }
          
          if (      aValue == null) {
                    aValue = new Array(MALength);
          }
          if (      getBarState() == BARSTATE_NEWBAR) {
                    aValue.pop();  
                    aValue.unshift(vValue);
          } else {
                aValue[0] = vValue;
          }

          for(      i = 0; i < MALength; i++) {
                    vSum += aValue[i];
          }
          
          var       vMA = (vSum/MALength);
          
          
          if(      MAType=="Exponential"){
              if(      aValue[MALength-1] != null) vEMA = EMA(MALength, aValue); 
              return       vEMA;
          }else{
              return       vMA;
          }
          return new Array(      vValue, vMA);
          
      }


      function       EMA(MALength, aValue) {

          var       dSum = 0.0;

          if(      getBarState() == BARSTATE_ALLBARS || bPrimed == false) {
                    dPercent = (2.0 / (MALength + 1.0));
                    bPrimed = false;
          }

          if (      getBarState() == BARSTATE_NEWBAR) {
                    vEMA1 = vEMA;
          }

          if(      bPrimed == false) {
              for(var       i = 0; i < MALength; i++) {
                        dSum += aValue[i];
              }
                    bPrimed = true;
              return (      dSum / MALength);
          } else {
              return (((      vValue - vEMA1) * dPercent) + vEMA1);
          }
      } 

      Comment

      • #4
        Nooze
        The enclosed revision should now work
        Alex

        PHP Code:
        /************************************************
        Alexis C. Montenegro © August 2004                        
        Use and/or modify this code freely. If you redistribute it
        please include this and/or any other comment blocks and a 
        description of any changes you make.                      
         *****************************************************/

        var vMA1 = null;
        var         vMA2 = null;

        function         preMain() {

                    setStudyTitle("PPO");
                    setShowCursorLabel(false);
                    setDefaultBarStyle(PS_SOLID, 0);
                    setDefaultBarFgColor(Color.yellow, 0);
                    setDefaultBarThickness(1, 0);
                    setPlotType(PLOTTYPE_LINE, 0);
                    //setPlotType(PLOTTYPE_HISTOGRAM); 
            //checkVersion(1,"http://share.esignal.com/ContentRoot/ACM%20Test/Formulas/basicMAx2.efs"); //Comment this line out if modifying the code
                
                    var fp1 = new FunctionParameter("MALength", FunctionParameter.NUMBER);
                    fp1.setLowerLimit(1);        
                    fp1.setDefault(9);
            
            var         fp2 = new FunctionParameter("MAType", FunctionParameter.STRING);
                    fp2.setName("MAType");
                    fp2.addOption("Simple");
                    fp2.addOption("Exponential");
                    fp2.setDefault("Exponential"); //Edit this value to set a new default

                    var fp3 = new FunctionParameter("MA1Length", FunctionParameter.NUMBER);
                    fp3.setLowerLimit(1);        
                    fp3.setDefault(12); //Edit this value to set a new default
            
                    var fp4 = new FunctionParameter("MA1Source", FunctionParameter.STRING);
                    fp4.setName("MA1Source");
                    fp4.addOption("Close");
                    fp4.addOption("High");
                    fp4.addOption("Low");
                    fp4.addOption("Open");
                    fp4.addOption("HL/2");
                    fp4.addOption("HLC/3");
                    fp4.addOption("OHLC/4");
                    fp4.setDefault("Close"); //Edit this value to set a new default     
            
                    var fp5 = new FunctionParameter("MA1Type", FunctionParameter.STRING);
                    fp5.setName("MA1Type");
                    fp5.addOption("MAStudy.SIMPLE");
                    fp5.addOption("MAStudy.EXPONENTIAL");
                    fp5.addOption("MAStudy.WEIGHTED");
                    fp5.addOption("MAStudy.VOLUMEWEIGHTED");
                    fp5.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default
            
                    var fp6 = new FunctionParameter("MA2Length", FunctionParameter.NUMBER);
                    fp6.setLowerLimit(1);        
                    fp6.setDefault(26); //Edit this value to set a new default
            
                    var fp7 = new FunctionParameter("MA2Source", FunctionParameter.STRING);
                    fp7.setName("MA1Source");
                    fp7.addOption("Close");
                    fp7.addOption("High");
                    fp7.addOption("Low");
                    fp7.addOption("Open");
                    fp7.addOption("HL/2");
                    fp7.addOption("HLC/3");
                    fp7.addOption("OHLC/4");
                    fp7.setDefault("Close"); //Edit this value to set a new default
            
                    var fp8 = new FunctionParameter("MA2Type", FunctionParameter.STRING);
                    fp8.setName("MA2Type");
                    fp8.addOption("MAStudy.SIMPLE");
                    fp8.addOption("MAStudy.EXPONENTIAL");
                    fp8.addOption("MAStudy.WEIGHTED");
                    fp8.addOption("MAStudy.VOLUMEWEIGHTED");
                    fp8.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default
                
               
        }

        var         bPrimed = false; 
        var         vEMA = null;
        var         vEMA1 = null;   
        var         dPercent = 0.0;
        var         vValue = 0.0;
        var         aValue = null;
        var         vAvg = null;//used in the example provided

        function  main(MALength,MAType,MA1Length,MA1Source,MA1Type,MA2Length,MA2Source,MA2Type) {

            var         i;
            var         vSum = 0.0;
            
                    //insert below the calculations required for the user defined variable (example provided)
                    if (vMA1 == null) vMA1 = new MAStudy(MA1Length, MA1Source, eval(MA1Type));
            if (        vMA2 == null) vMA2 = new MAStudy(MA2Length, MA2Source, eval(MA2Type));
            
            var         Avg1 = vMA1.getValue(MAStudy.MA)
            if(        Avg1 == null) return;
            var         Avg2 = vMA2.getValue(MAStudy.MA);
            if(        Avg2 == null) return;
            
                    vAvg = (Avg1-Avg2)/Avg1;
            
                    //end section for user defined variable

                    vValue = vAvg; //replace vAvg with the user defined variable

                    if(vValue == null) {
                return;
            }
            
            if (        aValue == null) {
                        aValue = new Array(MALength);
            }
            if (        getBarState() == BARSTATE_NEWBAR) {
                        aValue.pop();  
                        aValue.unshift(vValue);
            } else {
                    aValue[0] = vValue;
            }

            for(        i = 0; i < MALength; i++) {
                        vSum += aValue[i];
            }
            
            var         vMA = (vSum/MALength);
            
            
            if(        MAType=="Exponential"){
                if(        aValue[MALength-1] != null) vEMA = EMA(MALength, aValue); 
                return new Array(         vValue,vEMA);
            }else{
                return new Array (        vValue,vMA);
            }
        }


        function         EMA(MALength, aValue) {

            var         dSum = 0.0;

            if(        getBarState() == BARSTATE_ALLBARS || bPrimed == false) {
                        dPercent = (2.0 / (MALength + 1.0));
                        bPrimed = false;
            }

            if (        getBarState() == BARSTATE_NEWBAR) {
                        vEMA1 = vEMA;
            }

            if(        bPrimed == false) {
                for(var         i = 0; i < MALength; i++) {
                            dSum += aValue[i];
                }
                        bPrimed = true;
                return (        dSum / MALength);
            } else {
                return (((        vValue - vEMA1) * dPercent) + vEMA1);
            }
        } 

        Comment

        • #5
          Nooze
          FWIW you could have also written this section

          PHP Code:
          //insert below the calculations required for the user defined variable (example provided)
                        if (vMA1 == null) vMA1 = new MAStudy(MA1Length, MA1Source, eval(MA1Type));
              if (          vMA2 == null) vMA2 = new MAStudy(MA2Length, MA2Source, eval(MA2Type));
              
              var           Avg1 = vMA1.getValue(MAStudy.MA)
              if(          Avg1 == null) return;
              var           Avg2 = vMA2.getValue(MAStudy.MA);
              if(          Avg2 == null) return;
              
                        vAvg = (Avg1-Avg2)/Avg1;
              
                        //end section for user defined variable 
          in the following way

          PHP Code:
          //insert below the calculations required for the user defined variable (example provided)
                        if (vMA1 == null) vMA1 = new MAStudy(MA1Length, MA1Source, eval(MA1Type));
              if (          vMA2 == null) vMA2 = new MAStudy(MA2Length, MA2Source, eval(MA2Type));
              
                  
                        vAvg = (vMA1.getValue(MAStudy.MA)-vMA2.getValue(MAStudy.MA))/vMA1.getValue(MAStudy.MA);
              
                        //end section for user defined variable 
          which is how you had it at one point
          Hope this helps
          Alex

          Comment

          • #6
            Hi,

            Alex, I understand my mistake in syntax... but still I have different value for the indicator PPO in eSignal and TradeStation.

            I can't find what is I wrong... So, I can't trade at full capacity wihtout this indicator.

            Your help will be invaluable!

            Thank you!

            PPO code (EasyLanguage)

            Code:
             Inputs: Len1(12), Len2(26), LenSig(9);

Value1 = (XAverage(C,Len1)-XAverage(C,Len2))/XAverage(C,Len1);
Value2 = XAverage(Value1,LenSig);
Value3 = (Value1-Value2);

Plot1(Value1, "PPO", cyan);
Plot2(Value2, "Sig", red);
Plot3(Value3, "Hist", 16);
            PPO code (eSignal)

            PHP Code:
            /************************************************
            Alexis C. Montenegro © August 2004                        
            Use and/or modify this code freely. If you redistribute it
            please include this and/or any other comment blocks and a 
            description of any changes you make.                      
              *****************************************************/

            var vMA1 = null;
            var             vMA2 = null;

            function             preMain() {

                            setStudyTitle("PPO");
                            setShowCursorLabel(false);
                            setDefaultBarFgColor(Color.cyan,0); 
                            setDefaultBarFgColor(Color.red,1); 
                            setDefaultBarFgColor(Color.lightgrey,2);
                            //addBand(0, PS_SOLID, 1, Color.lightgrey,"zero"); 
                            setDefaultBarThickness(2,0);
                            setDefaultBarThickness(1,1);
                            setDefaultBarThickness(2,2);
                            setPlotType(PLOTTYPE_HISTOGRAM,2);
                            //checkVersion(1,"http://share.esignal.com/ContentRoot/ACM%20Test/Formulas/basicMAx2.efs"); //Comment this line out if modifying the code
                    
                            var fp1 = new FunctionParameter("MALength", FunctionParameter.NUMBER);
                            fp1.setLowerLimit(1);        
                            fp1.setDefault(9);
                
                var             fp2 = new FunctionParameter("MAType", FunctionParameter.STRING);
                            fp2.setName("MAType");
                            fp2.addOption("Simple");
                            fp2.addOption("Exponential");
                            fp2.setDefault("Exponential"); //Edit this value to set a new default

                            var fp3 = new FunctionParameter("MA1Length", FunctionParameter.NUMBER);
                            fp3.setLowerLimit(1);        
                            fp3.setDefault(12); //Edit this value to set a new default
                
                            var fp4 = new FunctionParameter("MA1Source", FunctionParameter.STRING);
                            fp4.setName("MA1Source");
                            fp4.addOption("Close");
                            fp4.addOption("High");
                            fp4.addOption("Low");
                            fp4.addOption("Open");
                            fp4.addOption("HL/2");
                            fp4.addOption("HLC/3");
                            fp4.addOption("OHLC/4");
                            fp4.setDefault("Close"); //Edit this value to set a new default     
                
                            var fp5 = new FunctionParameter("MA1Type", FunctionParameter.STRING);
                            fp5.setName("MA1Type");
                            fp5.addOption("MAStudy.SIMPLE");
                            fp5.addOption("MAStudy.EXPONENTIAL");
                            fp5.addOption("MAStudy.WEIGHTED");
                            fp5.addOption("MAStudy.VOLUMEWEIGHTED");
                            fp5.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default
                
                            var fp6 = new FunctionParameter("MA2Length", FunctionParameter.NUMBER);
                            fp6.setLowerLimit(1);        
                            fp6.setDefault(26); //Edit this value to set a new default
                
                            var fp7 = new FunctionParameter("MA2Source", FunctionParameter.STRING);
                            fp7.setName("MA1Source");
                            fp7.addOption("Close");
                            fp7.addOption("High");
                            fp7.addOption("Low");
                            fp7.addOption("Open");
                            fp7.addOption("HL/2");
                            fp7.addOption("HLC/3");
                            fp7.addOption("OHLC/4");
                            fp7.setDefault("Close"); //Edit this value to set a new default
                
                            var fp8 = new FunctionParameter("MA2Type", FunctionParameter.STRING);
                            fp8.setName("MA2Type");
                            fp8.addOption("MAStudy.SIMPLE");
                            fp8.addOption("MAStudy.EXPONENTIAL");
                            fp8.addOption("MAStudy.WEIGHTED");
                            fp8.addOption("MAStudy.VOLUMEWEIGHTED");
                            fp8.setDefault("MAStudy.EXPONENTIAL"); //Edit this value to set a new default
                    
                   
            }

            var             bPrimed = false; 
            var             vEMA = null;
            var             vEMA1 = null;   
            var             dPercent = 0.0;
            var             vValue = 0.0;
            var             aValue = null;
            var             vAvg = null;//used in the example provided

            function   main(MALength,MAType,MA1Length,MA1Source,MA1Type,MA2Length,MA2Source,MA2Type) {

                var             i;
                var             vSum = 0.0;
                
                            //insert below the calculations required for the user defined variable (example provided)
                            if (vMA1 == null) vMA1 = new MAStudy(MA1Length, MA1Source, eval(MA1Type));
                if (            vMA2 == null) vMA2 = new MAStudy(MA2Length, MA2Source, eval(MA2Type));
                
                var             Avg1 = vMA1.getValue(MAStudy.MA)
                if(            Avg1 == null) return;
                var             Avg2 = vMA2.getValue(MAStudy.MA);
                if(            Avg2 == null) return;
                
                            vAvg = (Avg1-Avg2)/Avg1;
                
                            //end section for user defined variable

                            vValue = vAvg; //replace vAvg with the user defined variable

                            if(vValue == null) {
                    return;
                }
                
                if (            aValue == null) {
                                aValue = new Array(MALength);
                }
                if (            getBarState() == BARSTATE_NEWBAR) {
                                aValue.pop();  
                                aValue.unshift(vValue);
                } else {
                            aValue[0] = vValue;
                }

                for(            i = 0; i < MALength; i++) {
                                vSum += aValue[i];
                }
                
                var             vMA = (vSum/MALength);
                
                
                if(            MAType=="Exponential"){
                    if(            aValue[MALength-1] != null) vEMA = EMA(MALength, aValue); 
                    return new Array(             vValue,vEMA, (vValue-vEMA));
                }else{
                    return new Array (            vValue,vMA, (vValue-vMA));
                }
            }


            function             EMA(MALength, aValue) {

                var             dSum = 0.0;

                if(            getBarState() == BARSTATE_ALLBARS || bPrimed == false) {
                                dPercent = (2.0 / (MALength + 1.0));
                                bPrimed = false;
                }

                if (            getBarState() == BARSTATE_NEWBAR) {
                                vEMA1 = vEMA;
                }

                if(            bPrimed == false) {
                    for(var             i = 0; i < MALength; i++) {
                                    dSum += aValue[i];
                    }
                                bPrimed = true;
                    return (            dSum / MALength);
                } else {
                    return (((            vValue - vEMA1) * dPercent) + vEMA1);
                }
            } 
            See charts:



            Comment

            • #7
              Nooze
              The errors are in the missing Offset parameter in these two lines

              if (vMA1 == null) vMA1 = new MAStudy(MA1Length, MA1Source, eval(MA1Type));
              if (vMA2 == null) vMA2 = new MAStudy(MA2Length, MA2Source, eval(MA2Type));

              which need to be replaced with the following

              if (vMA1 == null) vMA1 = new MAStudy(MA1Length, 0, MA1Source, eval(MA1Type));
              if (vMA2 == null) vMA2 = new MAStudy(MA2Length, 0, MA2Source, eval(MA2Type));

              I believe this will take care of the issue
              Alex

              Comment

              • #8
                Alex, you are great!

                It's exactly what I need...

                Thank you again!

                Best wishes,

                Comment

                • #9
                  Nooze
                  My pleasure and thank you for the compliment.
                  Alex

                  Comment

                  • #10
                    Hi Alex,

                    I'd like to ask you one more question... I find your EFS "2daybar_box" very interesting ... and I have slightly modified it (add mid range line and remove "SetBarColor") because I intend to use this indicator for intraday...

                    Unfortunately, I have a problem: this plot does not update on every bar (I attached an example).

                    Can I solve this problem without rewriting the entire code.

                    Thank you in advance!

                    Best wishes,


                    Comment

                    • #11
                      Nooze
                      The easiest solution is to add setComputeOnClose(); in preMain(). This will leave the current bar "unboxed" but as soon as that is completed the boxes will update.
                      Alex

                      Comment

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