二進のπ

binary-pi.rb

# 二進のπ
# Inspired from https://twitter.com/indozou/status/1520073427172093952
#
# Copyright 2022 <zundan at gmail.com>
#
# Permission is granted for use, copying, modification, distribution,
# and distribution of modified versions of this work as long as the
# above copyright notice is included.

class Numeric
  def to_s_radix(radix = 10, n_frac = 31)
    x = self.abs
    r = self < 0 ? "-" : ""

    c = x.floor
    r += c.to_s(radix)
    x -= c

    r += "." if x > 0
    while x > 0 and n_frac > 0
      x *= radix
      c = x.floor
      r += c.to_s(radix)
      x -= c
      n_frac -= 1
    end

    return r
  end
end

puts Math::PI.to_s_radix(2)