From: "mrkn (Kenta Murata)" <noreply@...>
Date: 2022-04-20T02:04:05+00:00
Subject: [ruby-core:108304] [Ruby master Bug#18677] BigDecimal#power (**) returns FloatDomainError when passing an infinite parameter

Issue #18677 has been updated by mrkn (Kenta Murata).


I made a patch at https://github.com/ruby/bigdecimal/pull/227.

Note that the last case `-1 ** BigDecimal::INFINITY` should cause `Math::DomainError`.

----------------------------------------
Bug #18677: BigDecimal#power (**) returns FloatDomainError when passing an infinite parameter
https://bugs.ruby-lang.org/issues/18677#change-97323

* Author: dorianmariefr (Dorian Mari��)
* Status: Assigned
* Priority: Normal
* Assignee: mrkn (Kenta Murata)
* ruby -v: ruby 3.1.1p18 (2022-02-18 revision 53f5fc4236) [x86_64-darwin21]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
Example:

```ruby
> BigDecimal(10) ** BigDecimal("Infinity")
FloatDomainError: Computation results in 'Infinity'
```

Maybe:

```ruby
require "bigdecimal/util"

class BigDecimal < Numeric
  def **(other)
    if other.infinite? == 1
      if self > 1
        BigDecimal::INFINITY
      elsif self == 1
        self
      elsif self >= 0
        BigDecimal(0)
      else
        power(other)
      end
    else
      power(other)
    end
  end
end

def puts_and_eval(string)
  puts string
  p eval(string)
end

puts_and_eval "10 ** BigDecimal::INFINITY"
puts_and_eval "1 ** BigDecimal::INFINITY"
puts_and_eval "0.1 ** BigDecimal::INFINITY"
puts_and_eval "0 ** BigDecimal::INFINITY"
puts_and_eval "-1 ** BigDecimal::INFINITY"
```

Seems like ruby is doing very different things from math though



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