Find a square root with elixir (or just call :math.sqrt/1)

sqrt.exs

 defmodule Math do

  def sqrt(x) do
    refine x, x / 2.0, 1.0
  end

  def refine(target, _, attempt) when attempt * attempt == target do
    attempt
  end

  def refine(_, adjustment, attempt) when abs(attempt - (attempt - adjustment)) < 1.0e-20 do
    attempt
  end

  def refine(target, adjustment, attempt) when attempt*attempt > target do 
    refine(target, adjustment / 2, attempt - adjustment) 
  end

  def refine(target, adjustment, attempt) when attempt*attempt < target do
    refine(target, adjustment, attempt + adjustment) 
  end

end