/*********************************************************
Alexis C. Montenegro © October 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(true);
    setStudyTitle("Standard Error Bands");
    setCursorLabelName("Up-SEB",0);
    setCursorLabelName("Lo-SEB",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("Smooth", FunctionParameter.NUMBER);
	with(fpArray[x++]){
        setLowerLimit(1);		
        setDefault(3);
    }
	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("close"); 
    }
	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 xLib1 = addLibrary("amStudies.efsLib");
var xLib2 = addLibrary("amFunctions.efsLib");
var bInit = false;
var xBands = null;
var xBandsU = null;
var xBandsL = null;

function main(Length,Smooth,Source,Symbol,Interval,Params){
    if(bInit==false){
        if(Symbol == null) Symbol = getSymbol();
        if(Interval == null) Interval = getInterval();
        var vSymbol = Symbol+","+Interval;
        xBands = efsInternal("calcBands",Length,Smooth,Source,sym(vSymbol));
        xBandsU = getSeries(xBands,0)
        xBandsL = getSeries(xBands,1)
        setShowTitleParameters(eval(Params));
        bInit=true;
    }
    return new Array (xBandsU,xBandsL)
}

var xInit = false;
var xAvg  = null;
var xStdErr = null

function calcBands(length,smooth,source,series){
    if(xInit==false){
        xAvg = sma(smooth,xLib1.amLSMA(length,eval(source)()));
        xStdErr = xLib2.amStdErr(length,smooth,eval(source)());
        xInit=true;
    }
    if(xAvg.getValue(0)==null) return;
    var Upper = xAvg.getValue(0)+(2*xStdErr.getValue(0));
    var Lower = xAvg.getValue(0)-(2*xStdErr.getValue(0));
    return new Array (Upper,Lower);
}