DateVector gies you the ability to generate lists of dates matching a particular pattern, i.e. every friday, every 3rd friday, every 2nd and 17th of every 2nd month and so on.
DateVector.new takes 6 arguments. They are
every => an Integer or array of Integers
what => a Symbol. one of :day, :monday, :tuesday, :wednesday, :thursday, :friday, :saturday, :sunday
of_every => an Integer
period => :week or :month
start_date => a Date
end_date => a Date
d1 = Date.today; d2 = d1 + 365
dv1 = DateVector.new(1,:friday, 1, :week, d1, d2) # every friday
dv2 = DateVector.new(1,:friday, 2, :week, d1, d2) # every 2nd friday
dv3 = DateVector.new(15,:day, 1, month, d1, d2) # 15th of every month
dv4 = DateVector.new([7,22],:day, 1, month, d1, d2) # 7th and 22nd of every month
dv5 = DateVector.new([7,22],:day, 3, month, d1, d2) # 7th and 22nd of every 3 months
dv6 = DateVector.new([2,4],:friday, 1, :month, d1, d2) # every 2nd and 4th friday of every month
all_dates = dv1.get_dates #gets all dates specified
some_dates = dv1(d1+30, d2-30) # gets dates between dates specified