[ruby-core:97463] [Ruby master Bug#16677] Negative integer powered (**) to a float number results in a complex

Issue #16677 has been updated by sawa (Tsuyoshi Sawada).


I think the issue is this:

`**` has higher precedence than `-` adjacent to a numerical,

```ruby
-2 ** 2 # => -4
(-2) ** 2 # => 4
-(2 ** 2) # => -4
```

and `-` adjacent to a numerical has higher precedence than a typical method call (i.e., one that uses a period `.`):

```ruby
-2.2.ceil # => -2
(-2.2).ceil # => -2
-(2.2.ceil) # => -3
```

Our intuition suggests that precedence relation should be transitive. If that were the case, then `**` should have higher precedence than `-` and a method call (although the latter does not make sense because a non-applied method cannot be combined with `**` excluding its receiver; see below).

However, when both `-` adjacent to a numerical and a method call appear together, `**` has lower precedence than either:

```ruby
-2.itself ** 2 # => 4
((-2).itself) ** 2 # => 4
-(2.itself ** 2) # => -4
```

So, a natural suggestion might be to let `**` have higher precedence than `-` even when there is an intervening method as follows:

```ruby
-2.itself ** 2 # => -(2.itself ** 2) # => -4

```

----------------------------------------
Bug #16677: Negative integer powered (**) to a float number results in a complex 
https://bugs.ruby-lang.org/issues/16677#change-84607

* Author: CamilleDrapier (Camille Drapier)
* Status: Open
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* ruby -v: 2.5.7, 2.6.5, 2.7.0
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
Not sure if this is an unexpected behavior.

This works as I expect:

```
-2 ** 2.2 # => -4.59479341998814
```

But when I change the code a bit, it gives me a complex:

```ruby
-2.to_i ** 2.2 # => (3.717265962412589+2.7007518095995273i)

a = -2; a ** 2.2 # => (3.717265962412589+2.7007518095995273i)
```

This seems to happen only with negative numbers and float powers. I think it might be related to how `Fixnum` is treated differently from other classes by the power function.



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