-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=62102

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-- Indicator profile initialization routine
-- Defines indicator profile properties and indicator parameters
-- TODO: Add minimal and maximal value of numeric parameters and default color of the streams
function Init()
    indicator:name("Standard Error Bands");
    indicator:description("Standard Error Bands");
    indicator:requiredSource(core.Tick);
    indicator:type(core.Indicator);
    indicator.parameters:addGroup("Calculation");	
    indicator.parameters:addInteger("Period", "Period", "Period", 21);
    indicator.parameters:addInteger("Smoothing", "Smoothing period", "Smoothing period", 3);
    indicator.parameters:addDouble("Multiplier", "Multiplier", "Multiplier", 2);
	indicator.parameters:addGroup("Style");	
    indicator.parameters:addColor("Top_color", "Color of Top", "Color of Top", core.rgb(0, 255, 0));
	indicator.parameters:addInteger("width1", "Line width", "", 1, 1, 5);
    indicator.parameters:addInteger("style1", "Line style", "", core.LINE_SOLID);
    indicator.parameters:setFlag("style1", core.FLAG_LINE_STYLE);
	
    indicator.parameters:addColor("Central_color", "Color of Central", "Color of Central", core.rgb(0, 0, 255));
	indicator.parameters:addInteger("width2", "Line width", "", 1, 1, 5);
    indicator.parameters:addInteger("style2", "Line style", "", core.LINE_SOLID);
    indicator.parameters:setFlag("style2", core.FLAG_LINE_STYLE);
	
    indicator.parameters:addColor("Bottom_color", "Color of Bottom", "Color of Bottom", core.rgb(255, 0, 0));
	indicator.parameters:addInteger("width3", "Line width", "", 1, 1, 5);
    indicator.parameters:addInteger("style3", "Line style", "", core.LINE_SOLID);
    indicator.parameters:setFlag("style3", core.FLAG_LINE_STYLE);
end

-- Indicator instance initialization routine
-- Processes indicator parameters and creates output streams
-- TODO: Refine the first period calculation for each of the output streams.
-- TODO: Calculate all constants, create instances all subsequent indicators and load all required libraries
-- Parameters block
local Period;
local Smoothing;
local Multiplier;

local first;
local source = nil;

-- Streams block
local Top = nil;
local Central = nil;
local Bottom = nil;
local Raw;
-- Routine
function Prepare(nameOnly)
    Period = instance.parameters.Period;
    Smoothing = instance.parameters.Smoothing;
    Multiplier = instance.parameters.Multiplier;
    source = instance.source;
	
    first = source:first()+Period;

	
	
    local name = profile:id() .. "(" .. source:name() .. ", " .. tostring(Period) .. ", " .. tostring(Smoothing) .. ", " .. tostring(Multiplier) .. ")";
    instance:name(name);
    
	if   (nameOnly) then
        return;
    end
	
	Raw = instance:addInternalStream(first, 0);
   
        Top = instance:addStream("Top", core.Line, name .. ".Top", "Top", instance.parameters.Top_color, first+Smoothing);
		Top:setWidth(instance.parameters.width1);
        Top:setStyle(instance.parameters.style1);
		
        Central = instance:addStream("Central", core.Line, name .. ".Central", "Central", instance.parameters.Central_color, first+Smoothing);
		Central:setWidth(instance.parameters.width2);
        Central:setStyle(instance.parameters.style2);
		
        Bottom = instance:addStream("Bottom", core.Line, name .. ".Bottom", "Bottom", instance.parameters.Bottom_color, first+Smoothing);
		Bottom:setWidth(instance.parameters.width3);
        Bottom:setStyle(instance.parameters.style3);
		
   
end

-- Indicator calculation routine
-- TODO: Add your code for calculation output values
function Update(period)

    if period < first or not source:hasData(period) then
	return;
	end
	
	Raw[period]= mathex.lreg (source, period-Period+1, period);
	
	 if period < first + Smoothing then
	 return;
	 end
	
	
       
        Central[period] = mathex.avg(Raw, period-Smoothing+1,period);
		local Deviation= mathex.stdev (Raw, period-Smoothing+1,period); 
		Top[period] = Central[period]+ Multiplier* Deviation;
        Bottom[period] = Central[period]- Multiplier* Deviation;
    
end