From: "Christoffer Lernö" <lerno@...>
Date: 2007-02-27T22:13:29+09:00
Subject: Re: generating negative random numbers


On Jan 30, 2007, at 08:52 , Martin DeMello wrote:

> On 1/30/07, Josselin <josselin@wanadoo.fr> wrote:
>> I know how to generate positive random numbers, but is it possible to
>> generate a random number in a range such  [-9..+9]   ?
>> tfyh
>
> class Range
>  def rand
>    Kernel::rand(last - first + 1) + first
>  end
> end
>
> (-9..9).rand

(-9...10).rand won't give the expected answer. I think the below  
should fix the problem when the last entry in the range is excluded:

class Range
  def rand
    return first if exclude_end? && last == first
    Kernel::rand(last - first + (exclude_end? ? 0 : 1)) + first
  end
end