README.md

Concurrent calculation of Fibonacci in Elixir up to the 1200th position (faster than you can see)

It uses a known formla to evaluate a position instead of calculating it in a sequencial and/or recursive approach.

It's amazing how fast it is:

concurrent_fibonacci.ex

defmodule ConcurrentFibonacci do
  def start do
    parallel_map(1..1200, fn(x) ->
      "Fibonacci of #{x} is: #{FibonacciCalculus.of(x)}"
    end)
  end

  def parallel_map(list, func) do
    list |> Enum.map(fn e -> spawn(fn ->
      IO.puts func.(e)
    end) end)
  end
end

fibonacci_calculus.ex

defmodule FibonacciCalculus do
  @golden_n :math.sqrt(5)

  def of(n) do
    (x_of(n) - y_of(n)) / @golden_n
  end

  def x_of(n) do
    :math.pow((1 + @golden_n) / 2, n)
  end

  def y_of(n) do
    :math.pow((1 - @golden_n) / 2, n)
  end
end