Revision 3 calcs to n = 2**18 - 1

TrialFactorisation.rb

#require 'prime'
include Math

print "\uFEFF[#{RUBY_VERSION}]\n"
# Fixnum < 2**30 <= Bignum
n = rand(9999..375999) # 25326001 ## Memory limit exceeded
m = 2**n - 1 #! n != Bignum

  def prime? num
    # For larger values method performs significantly slower
    # //github.com/ruby/ruby/pull/1786/
    return false if num < 2
    return true if num == 2 or num == 3
    return false if num %2 == 0 or num %3 == 0
    i = 5; w = 2
    while i * i <= num
      return false if num %i == 0
      i += w; w = 6 - w
    end
    
    limit = sqrt(num).to_i # Float -> Fixnum
    5.step(limit, 2) do |d|
      return false if num %d == 0
    end
    true
  end
  
  #! Dividers output
  def cofactors num, prime=false, div=2
    factor = []
    unless prime?(num)
      for n in (2..num / 2)
        factor << n if num %n == 0
        return if div > factor[0] unless factor.empty?
        factor.pop if num %n == 0 and prime unless prime?(n)
      end
      product = true if num == factor.inject(){|res, el| res * el}
      puts "#{num} #{'co' if prime && product}factors #{factor.reverse.inspect}"
    else
      puts "#{num} is Prime"
    end
  end

#! Result
#puts "", "M#{n} is #{'not ' unless prime?m}Prime"

#! Debug
LIMIT_DIVISION = 7
n.upto(n + 60 + LIMIT_DIVISION) do |i|
  cofactors i, true, LIMIT_DIVISION
  #puts i.prime_division.inspect
end