Exclusive float range, Range#step result in counterintuitive result

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From	Joey Zhou <yimutang@gmail.com>
Newsgroups	comp.lang.ruby
Subject	Exclusive float range, Range#step result in counterintuitive result
Date	Thu, 14 Apr 2011 07:42:47 -0500
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Hi everybody,

I find that:

if
  range.exclude_end? == true
and
  [begin_obj, end_obj, step].grep(Float) != []
and
  [begin_obj, end_obj, step].any? {|f| f != f.to_i}
then
  # result will miss the last one
end

for example:

p (1...6.3).step.to_a # => [1.0, 2.0, 3.0, 4.0, 5.0], missing 6.0
p (1.1...6).step.to_a # => [1.1, 2.1, 3.1, 4.1], missing 5.1
p (1...6).step(1.1).to_a # => [1.0, 2.1, 3.2, 4.300000000000001],
missing 5.4

p (1.0...6.6).step(1.9).to_a # => [1.0, 2.9], missing 4.8
p (1.0...6.7).step(1.9).to_a # => [1.0, 2.9, 4.8], 6.7 == 4.8 + 1.9,
it's ok

The results seem so counterintuitive, is it a bug? Maybe I should report
it?

Thank you!

Joey

-- 
Posted via http://www.ruby-forum.com/.

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Thread

Exclusive float range, Range#step result in counterintuitive result Joey Zhou <yimutang@gmail.com> - 2011-04-14 07:42 -0500
  Re: Exclusive float range, Range#step result in counterintuitive result Joey Zhou <yimutang@gmail.com> - 2011-04-14 07:58 -0500
  Re: Exclusive float range, Range#step result in counterintuitive result Robert Klemme <shortcutter@googlemail.com> - 2011-04-14 08:28 -0500
  Re: Exclusive float range, Range#step result in counterintuitive result 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-14 11:47 -0500
  Re: Exclusive float range, Range#step result in counterintuitive result Su Zhang <zhangsu@live.com> - 2011-04-14 13:01 -0500

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