From: "Älphä Blüë" <jdezenzio@...>
Date: 2009-07-17T12:55:52+09:00
Subject: I have some Ruby math questions that need answering

When handling percentage calculations:

Simple 99/100..

Will I always have to do 99.to_f/100.to_f in order to receive 0.99?  Or
is there a simpler way of performing this task in ruby..

I notice that there doesn't appear to be a round method with decimal
places (or perhaps I can't find one) so I found this one which appears
to work:

class Float
  def round_to(x)
    (self * 10**x).round.to_f / 10**x
  end

  def ceil_to(x)
    (self * 10**x).ceil.to_f / 10**x
  end

  def floor_to(x)
    (self * 10**x).floor.to_f / 10**x
  end
end

The question I have is can I expand upon divisor behavior and create
something that changes the way ruby behaves with integers/floats on a
more permanent basis?

I only ask because I'm working with standard deviation and some advanced
mathematics that revolve around calculating variance.  I just don't want
to experience any gotchas halfway down my project.

Lastly, is there a good core site that houses all of the API for ruby
math functions or refined methods that deal with variance?

Many thanks.
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