From: fedorkk@...
Date: 2020-05-09T18:39:00+00:00
Subject: [ruby-core:98240] [Ruby master Bug#16843] A bug with floating point	multiplication

Issue #16843 has been updated by FedorKK (Fedor Koshel).


Ok, let's close it. It's really doesn't make any sense to improve the standard representation. But still:

``` go
func main() {
        fmt.Println(0.29 * 100 == 29.0)
}
true
```

``` ruby
irb(main):001:0> 0.29 * 100 == 29.0
=> false
```



----------------------------------------
Bug #16843: A bug with floating point multiplication
https://bugs.ruby-lang.org/issues/16843#change-85478

* Author: FedorKK (Fedor Koshel)
* Status: Open
* Priority: Normal
* ruby -v: 2.6.6, 2.7.1
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
I've reproduced it with both currently stable versions: 2.6.6 and 2.7.1.

``` ruby
irb(main):001:0> 0.29 * 100
=> 28.999999999999996
irb(main):002:0> 0.29 * 100.0
=> 28.999999999999996
irb(main):003:0> 0.28 * 100
=> 28.000000000000004
irb(main):004:0> 0.28 * 100.0
=> 28.000000000000004
irb(main):005:0> 0.27 * 100.0
=> 27.0
irb(main):006:0> 0.27 * 100
=> 27.0

$ ruby -v                                                                                                                                                                                                 
ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-linux]
```

``` ruby
irb(main):001:0> 0.29 * 100
=> 28.999999999999996
irb(main):002:0> 0.29 * 100.0
=> 28.999999999999996
irb(main):003:0> 0.28 * 100.0
=> 28.000000000000004
irb(main):004:0> 0.28 * 100
=> 28.000000000000004
irb(main):005:0> 0.27 * 100
=> 27.0
irb(main):006:0> 0.27 * 100.0
=> 27.0


$ ruby -v                                                                                                                                                                                                 
ruby 2.6.6p146 (2020-03-31 revision 67876) [x86_64-linux]
```





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