From: frosty <frosty@...>
Date: 2011-12-16T08:14:39+09:00
Subject: Re: round float to integer if whole number

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On 12/15/2011 05:21 AM, Gunther Diemant wrote:
>> That test does not work reliably:
> You're right, but floating point numbers don't work reliably (as
> one can see in your examples, one has always conversion and
> rounding errors)
> 
> Nonetheless if one has to work with floating point numbers it is
> surly better to define equality in terms of some delta error
> tolerance.
> 
I would think the most accurate way to do it would be to convert the
number to a string, split on the '.' and then check if a number
besides '0' is in the second part of the list. For example

irb(main):001:0> whole, nonwhole = 2.0 , 2.333
=> [2.0, 2.333]
irb(main):002:0> puts whole.class()
Float
=> nil
irb(main):003:0> puts nonwhole.class()
Float
=> nil
irb(main):004:0> whole_split = whole.to_s.split('.')[1]
=> "0"
irb(main):005:0> nonwhole_split = nonwhole.to_s.split('.')[1]
=> "333"
irb(main):006:0> /[1-9]/.match(whole_split)
=> nil
irb(main):007:0> /[1-9]/.match(nonwhole_split)
=> #<MatchData "3">

- -- 
frosty
public key: unluckyfrosty.net/public_key
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