Preferred number generator

preferred_numbers.rb

# https://en.wikipedia.org/wiki/Preferred_number

def preferred_numbers(x, precision=2)
  root = 10 ** (1 / x.to_f)
  return x.times.map {|i| (root ** i).round(precision)}
end

<<EXAMPLES

> preferred_numbers(2)
=> [1.0, 3.16]
> preferred_numbers(3)
=> [1.0, 2.15, 4.64]
> preferred_numbers(5)
=> [1.0, 1.58, 2.51, 3.98, 6.31]
> preferred_numbers(10)
=> [1.0, 1.26, 1.58, 2.0, 2.51, 3.16, 3.98, 5.01, 6.31, 7.94]

> preferred_numbers(3, 0)
=> [1, 2, 5]
# Like Euro denominations!

EXAMPLES