Issue #11995 has been updated by Nobuyoshi Nakada.

Status changed from Open to Rejected

The latter is parsed as `-(0.5**0.2)`.

~~~
$ ruby -e 'p (-0.5)**0.2'
(0.7042902001692478+0.5116967824803669i)
~~~

`Float#**` can result an imaginary number, but `BigDecimal` is only for real numbers.


----------------------------------------
Bug #11995: BigDecimal#power fails for some values
https://bugs.ruby-lang.org/issues/11995#change-56117

* Author: Evgeniy Dolzhenko
* Status: Rejected
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
$ irb -rbigdecimal
> BigDecimal('-0.5').power(BigDecimal('0.2'))
Math::DomainError: Zero or negative argument for log

but

> -0.5**0.2
=> -0.8705505632961241

The same is true for a few other exponent version I have tested. Is that feature or bug?



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