construct16.rb

def f2(n)
	return n.odd? ? (n * 3 + 1) / 2 : n / 2

end

def adj(x, m, n, s2, p2, p, x3)
	s2.replace(p[0...x] + (x3 % 2).to_s)
	m = (s2[x, 1] == p[x, 1])
	n = p2.reverse.to_i(2)
	p2[x, 1] = m ? '11' : '01'
	return m, n, x3
end

def terras121(p)
	
	p2 = ['01', '11'][p[0, 1].to_i]
	n = 1
	n3 = 0
	m = p2 == '11'
	x3 = (p2.reverse.to_i(2)) >> 1

	(1...p.length).each \
	{
		|x|

		if (!m)
			ns = n.to_s(2)
			ns[0, 1] = ''
			m1 = x3 - 3**n3
			n1 = f2(m1)
		end

		n3 = p[0...x].split('').select { |z| z == '1' }.size
		
		s2 = ''
		m, n, x3 = adj(x, m, n, s2, p2, p, m ? (f2(x3) + 3**n3) : (n1 + 3**n3))
	}

	n = p2.reverse.to_i(2)

	return n
end

def dense(w, d)
	w2 = w - 1
	
	a = (0...w2).to_a
	s = '0' * w2
	(1..(d * w - 1)).map { a.delete_at(rand(a.size)) }.each { |x| s[x, 1] = '1' }
	return ('1' + s)
	
end

def d(s)
        c = s.split('').select { |x| x == '1' }.size
	d = c.to_f / s.length
        return d
        
end

def len(ns, p)
	l = ns.split(p)
	l = [''] if (l.nil? || l.empty?)
	return l.map { |x| x.length }
end

def len01(ns)
	return len(ns, /0+/), len(ns, /1+/)
end

def e(ns)
	return len01(ns).flatten.size.to_f / ns.length
end

def avg(l)
	l.inject { |t, x| t + x }.to_f / l.size
end

def seq(n)
	n1 = n
	l = [n1]
	while (n != 1)
		n = f2(n)
		l << n
	end
	return l
end

f = File.open('gnuplot.cmd', 'w')
f.puts('$dat << eof')
f.puts(['d1', 'd2'].join("\t"))
w = 200
c = 100
c.times \
{
	|x|
	n = terras121(dense(w, x.to_f / (c - 1)))

	l = seq(n)
	a = avg(l[0...c].map { |x| d(x.to_s(2)) })
	b = avg(l[c..-1].map { |x| d(x.to_s(2)) })
	f.puts([a, b].join("\t"))
}

f.puts('eof')
f.puts("set colors classic; plot $dat using (column('d1')) with line lw 2, '' using (column('d2')) with line lw 2, 0.5 dt 3")
f.close