MiddleLine = EMA(N)
TopLile = MiddleLine + (D * StdDev)
BottomLine = MiddleLine — (D * StdDev)
D - standard deviations.
- Code: Select all
function Init()
indicator:name("Bollinger Bands with EMA");
indicator:description("Original Bollinger Bands with an EMA instead of a simple ma");
indicator:requiredSource(core.Tick);
indicator:type(core.Indicator);
indicator.parameters:addDouble("N", "Number of periods", "Number of periods", 20.0);
indicator.parameters:addDouble("Dev", "Number of standard deviations", "Number of standard deviations", 2.0);
indicator.parameters:addColor("clrBBP", "clrBBP", "clrBBP", core.rgb(255, 0, 0));
indicator.parameters:addColor("clrBBM", "clrBBM", "clrBBM", core.rgb(0, 255, 0));
indicator.parameters:addColor("clrBBA", "clrBBA", "clrBBA", core.rgb(0, 0, 255));
end
local N;
local D;
local first;
local source = nil;
local TL = nil;
local BL = nil;
local MA=nil;
-- Routine
function Prepare()
N = instance.parameters.N;
D = instance.parameters.Dev;
source = instance.source;
first = source:first()+N-1;
local name = "Bollinger Bands with EMA (" .. N .. ", " .. D .. ")";
instance:name(name);
MA = core.indicators:create("EMA", source, N);
TL = instance:addStream("TL", core.Line, name .. ".TL", "TL", instance.parameters.clrBBP, first)
BL = instance:addStream("BL", core.Line, name .. ".BL", "BL", instance.parameters.clrBBM, first)
AL = instance:addStream("AL", core.Line, name .. ".AL", "AL", instance.parameters.clrBBA, first)
end
-- Indicator calculation routine
function Update(period,mode)
MA:update(mode);
if(period >= first) then
local ml=MA.DATA[period];
local d = core.stdev(source, core.rangeTo(period, N));
TL[period] = ml + D * d;
BL[period] = ml - D * d;
AL[period] = ml;
end
end