[ruby-core:41573] [ruby-trunk - Bug #5713] Fixnum#** returns Infinity for 0 ** negative Bignum

Issue #5713 has been updated by Marc-Andre Lafortune.

Category set to core
Target version set to 2.0.0

John Firebaugh wrote:
> The execution path of 0 ** -Bignum goes to Rational(0) ** -Bignum, so I think the issue is there. I.e. Rational(0) ** -Bignum should raise ZeroDivisionError, the same as Rational(0) ** -Fixnum.

Yes, unless there is objection, Rational#** should treat 0 and 1 as special cases before resorting to conversion to float, i.e.

    Rational(0) ** (-2**100) # => Infinity, should raise an Error
    Rational(0) ** (2**100) # => 0.0, should be Rational(0)
    Rational(1) ** (2**100) # => 1.0, should be Rational(1)


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Bug #5713: Fixnum#** returns Infinity for 0 ** negative Bignum
http://redmine.ruby-lang.org/issues/5713

Author: John Firebaugh
Status: Open
Priority: Normal
Assignee: Marc-Andre Lafortune
Category: core
Target version: 2.0.0
ruby -v: ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-darwin10.8.0]


=begin
Instead it should raise ZeroDivisionError, the same as negative Fixnums.

 wordsize = 8 * 1.size
 fixnum_min = -2 ** (wordsize - 2)
 
 def zero_power(exp)
   0 ** exp
 rescue ZeroDivisionError
   "ZeroDivisionError"
 end
 
 [-1, fixnum_min, (fixnum_min-1)].each {|i| puts zero_power(i)}
=end



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