From: "alexandruanca (Alexandru Anca) via ruby-core" <ruby-core@...>
Date: 2023-01-07T14:48:24+00:00
Subject: [ruby-core:111728] [Ruby master Bug#19321] BigDecimal multiplication giving different result since Ruby 3.1

Issue #19321 has been updated by alexandruanca (Alexandru Anca).





> The old result was incorrect. The new, correct result is due to a bug fix.  I'm going to close this.  If you can find a result that is incorrect in Ruby 3.1 or 3.2, please post it.



I see, makes sence. Thanks for the explanation







----------------------------------------

Bug #19321: BigDecimal multiplication giving different result since Ruby 3.1

https://bugs.ruby-lang.org/issues/19321#change-101130



* Author: alexandruanca (Alexandru Anca)

* Status: Closed

* Priority: Normal

* ruby -v: 3.1.3

* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

----------------------------------------

I have this math operation 120.to_d * 0.07 and I noticed that since upgrading to Ruby 3.1 I get different results. I would expect to get the same result as in previous versions.

```

rbenv local 3.0.3

���  irb

require 'bigdecimal/util.rb'

(120.to_d * 0.07).to_s('F')

=> "8.4000000000000012"

```



```

rbenv local 3.1.3

��� irb

require 'bigdecimal/util.rb'

(120.to_d * 0.07).to_s('F')

=> "8.4"

```

It looks like the change has been introduced in Ruby 3.1. I tested Ruby 2.7.0 and I get the same result as in 3.0 ("8.4000000000000012")

I saw in the release notes that there were changes to bigdecimal so I am not sure if this is expected or it's a bug







-- 

https://bugs.ruby-lang.org/

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