/*********************************************************
Alexis C. Montenegro © September 2005                     
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 fpArray = new Array();

function preMain() {
    setPriceStudy(false);
    setStudyTitle("Fisher");
    setCursorLabelName("Fish",0);
    setCursorLabelName("Sig",1);
    setDefaultBarFgColor(Color.blue, 0);
    setDefaultBarFgColor(Color.red, 1);
    setPlotType(PLOTTYPE_LINE,0);
    setPlotType(PLOTTYPE_LINE,1);
    setDefaultBarThickness(1,0);
    setDefaultBarThickness(1,1);
    var x=0;
    fpArray[x] = new FunctionParameter("Length", FunctionParameter.NUMBER);
	with(fpArray[x++]){
        setLowerLimit(1);		
        setDefault(10);
    }
	fpArray[x] = new FunctionParameter("Source", FunctionParameter.STRING);
	with(fpArray[x++]){
        addOption("open"); 
        addOption("high");
        addOption("low");
        addOption("close");
        addOption("hl2");
        addOption("hlc3");
        addOption("ohlc4"); 
        setDefault("hl2"); 
    }
    fpArray[x] = new FunctionParameter("Symbol", FunctionParameter.STRING);
    with(fpArray[x++]){
        setDefault();
	}
	fpArray[x] = new FunctionParameter("Interval", FunctionParameter.STRING);
	with(fpArray[x++]){
        setDefault();
    }
    fpArray[x] = new FunctionParameter("Params", FunctionParameter.BOOLEAN);
	with(fpArray[x++]){
        setName("Show Parameters");
        setDefault(false);
    }
}

var bInit = false;
var Fish = null;

function main(Length,Source,Symbol,Interval,Params){
    if(bInit == false){
        if(Symbol == null) Symbol = getSymbol();
        if(Interval == null) Interval = getInterval();
        var vSymbol = Symbol+","+Interval;
        Fish = getSeries(efsInternal("calcFish",Length,eval(Source)(sym(vSymbol))));
        addBand(0, PS_SOLID, 1, Color.black,"0");
        setShowTitleParameters(eval(Params));
        bInit = true;
    }
    return new Array (Fish, Fish.getValue(-1));
}   

var xValue = 0;
var xValue_1 = 0;
var xFish = 0;
var xFish_1 = 0;
var xMaxH = null;
var xMinL = null;
var xInit = false;

function calcFish(length,source){
    if (xInit==false){
        xMaxH = upperDonchian(length,source);
        xMinL = lowerDonchian(length,source);
        xInit=true;
    }
    var nMaxH = xMaxH.getValue(0);
    var nMinL = xMinL.getValue(0);
    if (nMaxH==null || nMinL == null) return;
    if (getBarState()==BARSTATE_NEWBAR){
        xValue_1 = xValue;
        xFish_1 = xFish;
    }
    if (nMaxH-nMinL!=0){
        xValue = 0.33*2*((source.getValue(0)-nMinL)/(nMaxH-nMinL)-0.5)+0.67*xValue_1;
    }
    if (xValue > 0.99) xValue = 0.999;
    if (xValue < -0.99) xValue = -0.999;
    xFish = 0.5*Math.log((1+xValue)/(1-xValue))+0.5*xFish_1;
    return (xFish);
}