ruby implementation of exponential back off algorithm

exponential_backoff.rb

# EC = 1/2*(2**exp-1)
# ^equation

def exp_backoff(upto)
  
  result = [ ]
  # ^ stores wait periods

  (1..upto).each do |iter|
    result << (1.0/2.0*(2.0**iter - 1.0)).ceil
    # using ceil to round off
  end
  
  return result

end

# print a list containing wait durations
# these wait durations are in exponential increasing order
# exponential back off algorithm is used in networking hardware to augment successive waiting periods following failed connect attempts
# this implementation is for w3c validator script repo, even though 1 second wait period is enough while querying w3c api
# this is just for fun

puts exp_backoff(9)
# get waiting for periods for 9 tries

puts exp_backoff(3)[2]
# get the last and longest waiting period for three tries

How about:

result << (2**iter)/2