You probably want to use RollingFunctions
julia> using RollingFunctions
julia> prices = rand(100);
julia> moving_average = rollmean(prices, 20);
julia> moving_std = rollstd(prices, 20);
julia> bollinger_high = moving_average .+ 2moving_std;
julia> bollinger_low = moving_average .- 2moving_std;
julia> using Plots
julia> plot([moving_average bollinger_low bollinger_high], label = ["Moving average" "Low" "High"], ls = [:solid :dash :dash])