From: Joshua Ballanco <redmine@...>
Date: 2011-02-14T05:35:07+09:00
Subject: [ruby-core:35223] [Ruby 1.9-Bug#4394] Bug in floating point multiplication

Issue #4394 has been updated by Joshua Ballanco.


This is how floating point math works. See here for more info: http://en.wikipedia.org/wiki/Floating_point#Representable_numbers.2C_conversion_and_rounding

If you want exact decimal math, try:


ruby-1.9.2-p136 :001 > require 'bigdecimal'
 => true 
ruby-1.9.2-p136 :002 > (BigDecimal('12.4') * BigDecimal('1.05')).to_f
 => 13.02 

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http://redmine.ruby-lang.org/issues/show/4394

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