gistfile1.rb

#!/usr/bin/env ruby
# coding: utf-8

require 'pp'
require 'date'

def each_by_time(a, b)
  min_count = ((b - a) * 24*60).to_i + 1

  min_count.times.map{|t|
    a + Rational(t, 24*60)
  }
end

a = DateTime.new 2013, 10, 10, 12,  0, 0
b = DateTime.new 2013, 10, 10, 12, 10, 0

pp each_by_time(a, b)
# =>
# [#<DateTime: 2013-10-10T12:00:00+00:00 ((2456576j,43200s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:01:00+00:00 ((2456576j,43260s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:02:00+00:00 ((2456576j,43320s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:03:00+00:00 ((2456576j,43380s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:04:00+00:00 ((2456576j,43440s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:05:00+00:00 ((2456576j,43500s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:06:00+00:00 ((2456576j,43560s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:07:00+00:00 ((2456576j,43620s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:08:00+00:00 ((2456576j,43680s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:09:00+00:00 ((2456576j,43740s,0n),+0s,2299161j)>,
#  #<DateTime: 2013-10-10T12:10:00+00:00 ((2456576j,43800s,0n),+0s,2299161j)>]