28 lines
676 B
Plaintext
28 lines
676 B
Plaintext
defmodule Statistics do
|
|
def basic(n) do
|
|
{sum, sum2, hist} = generate(n)
|
|
mean = sum / n
|
|
stddev = :math.sqrt(sum2 / n - mean*mean)
|
|
|
|
IO.puts "size: #{n}"
|
|
IO.puts "mean: #{mean}"
|
|
IO.puts "stddev: #{stddev}"
|
|
Enum.each(0..9, fn i ->
|
|
:io.fwrite "~.1f:~s~n", [0.1*i, String.duplicate("=", trunc(500 * hist[i] / n))]
|
|
end)
|
|
IO.puts ""
|
|
end
|
|
|
|
defp generate(n) do
|
|
hist = for i <- 0..9, into: %{}, do: {i,0}
|
|
Enum.reduce(1..n, {0, 0, hist}, fn _,{sum, sum2, h} ->
|
|
r = :rand.uniform
|
|
{sum+r, sum2+r*r, Map.update!(h, trunc(10*r), &(&1+1))}
|
|
end)
|
|
end
|
|
end
|
|
|
|
Enum.each([100,1000,10000], fn n ->
|
|
Statistics.basic(n)
|
|
end)
|