Unbias a random generator: Difference between revisions

=={{header|Elixir}}==

<lang elixir>

defmodule Random do

def init() do

:random.seed(:erlang.now())

end

def randN(n) do

if Enum.member?(3..6, n) do

if :random.uniform(n) == 1, do: 1, else: 0

end

end

def unbiased(n) do

{x, y} = {randN(n), randN(n)}

if x != y, do: x, else: unbiased(n)

end

end

IO.puts "N biased unbiased"

Random.init()

for n <- 3..6 do

xs = for _ <- 1..10000, do: Random.randN(n)

ys = for _ <- 1..10000, do: Random.unbiased(n)

IO.puts "#{n} #{Enum.sum(xs) / Enum.count(xs)} #{Enum.sum(ys) / Enum.count(ys)}"

end

</lang>

Output:

<pre>

N biased unbiased

3 0.3356 0.5043

4 0.2523 0.4996

5 0.2027 0.5041

6 0.1647 0.4912

</pre>