pidigits Matz's Ruby #5 program

# The Computer Language Benchmarks Game
# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
# contributed by Aaron Tavistock

# Leverage GMP like all the other languages 
require 'gmp'

# Helpers that improve readability
class GMP::Z
  def mul!(a,b)
    GMP::Z.mul(self, a, b)
  end

  def times!(a)
    GMP::Z.mul(self, self, a)
  end
end

# Constants to reduce object instantiation and casting
ZERO = GMP::Z(0)
ONE = GMP::Z(1)
TWO = GMP::Z(2)
THREE = GMP::Z(3)
TEN = GMP::Z(10)

# Allocate these expensive objects once
@display_chunk = GMP::Z(0)
@k = GMP::Z(0)
@a = GMP::Z(0)
@t = GMP::Z(0)
@u = GMP::Z(0)
@k1 = GMP::Z(1)
@n = GMP::Z(1)
@d = GMP::Z(1)
@tmp = GMP::Z(0)

def next_chunk
  @tmp.mul!(@d, @t)
  @a.sub!(@tmp)
  @a.times!(TEN)
  @n.times!(TEN)
end

def produce_chunk
  @k.add!(ONE)
  @t.mul!(@n, TWO)
  @n.times!(@k)

  @a.add!(@t)
  @k1.add!(TWO)
  @a.times!(@k1)
  @d.times!(@k1)
  
  if @a >= @n
    @tmp.mul!(@n, THREE)
    @tmp.add!(@a)
    @t = @tmp.fdiv(@d)
    @u = @tmp.fmod(@d)
    @u.add!(@n)
    if @d > @u
      @display_chunk.times!(TEN)
      @display_chunk.add!(@t)
      return true
    end
  end
  
  false
end  

N = (ARGV[0] || 100).to_i
count = 0
while(count < N) do
  if produce_chunk
    count += 1
    if count % 10 == 0
      STDOUT.write "%010d\t:%d\n" % [@display_chunk.to_i, count]
      @display_chunk.times!(ZERO)
    end 
    next_chunk
  end
end

if @display_chunk.to_i > 0
  STDOUT.write "%s\t:%d\n" % [@display_chunk.to_s.ljust(10), count]
end
    

NOTES:
64-bit Ubuntu quad core
ruby 1.8.7 (2008-08-11 patchlevel 72) [x86_64-linux]
 
So old that I haven't been able to get rubygems to work
no backport, no gmp


Sun, 02 Jun 2019 06:21:56 GMT

COMMAND LINE:
/usr/bin/ruby pidigits.mri-5.mri 2000

PROGRAM FAILED 


PROGRAM OUTPUT:

pidigits.mri-5.mri:6:in `require': no such file to load -- gmp (LoadError)
	from pidigits.mri-5.mri:6