On the front page, I need to display the schedule of activities for
the current week. I am having issues figuring out how to get the dates
for the current week (with two seperate definitions: the first is
Sunday through Saturday, the other being Monday through Friday).
This isn't really a rails question so I'm not that surprised its not
in the books you've listed.
Rails has beginning_of_week, however that is one specific definition
of week. If you have a look inside it's easy to adapt that.
You just need to look at Time.now.wday, which varies from 0 (on a
sunday) to 6 (on a saturday).
So if your weeks start on thursday then you're looking for the
previous/next date with a wday of 4. You can do this naively by just
adding a day at a time until some_date.wday has the right value or you
can work out the increments yourself.
it's just arithmetic modulo 7. if d is the number of days until the
next thursday, and n is Time.now.wday then it must be that
n+d = 4 
so d = 4-n 
ie d = 4-n +k*7
for an appropriate value of k.
So days until thursdays are given by d=4-n + k*7.
If you want the next thursday then that imposes 7>=d >0
so if 0 <= n <4 (ie today is sunday through wednesday) then k = 0, so
d = 4 - Time.now.wday
if n>= 4 (thursday through saturday) then k = 1 so d = 11 -
and similarly for finding the previous thursday (this is probably an
overcomplicated way of reasoning about this - showing my background