require "table2"
local fmt = require "fmt"

local function cum_std_dev(a)
    for i = 1, #a do
        local b = a:slice(1, i)
        fmt.print("Values  : %,s", b)
        coroutine.yield(b:stddev())
    end
end

local a = {2, 4, 4, 4, 5,  5, 7, 9}
local co = coroutine.create(cum_std_dev)
while true do
    local _, sd = coroutine.resume(co, a)
    if !sd then break end
    fmt.print("Std Dev : %10.8f\n", sd)
end