Bug #7682

Inconsistent results when using variables versus raw floats in exponential calculations

Added by Chris Cashwell over 1 year ago. Updated over 1 year ago.

[ruby-core:51367]
Status:Rejected
Priority:Normal
Assignee:-
Category:-
Target version:1.9.3
ruby -v:ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.0] Backport:

Description

When performing exponential calculations using a negative number as the base, inconsistent results are returned when using the raw value as opposed to a variable containing the value.

In IRB:

1.9.3p194 :001 > -4.5 ** 0.5
=> -2.1213203435596424
1.9.3p194 :002 > foo = -4.5
=> -4.5
1.9.3p194 :003 > foo ** 0.5
=> (1.2989340843532398e-16+2.1213203435596424i)

The expected behavior is that these two calculations should be equivalent. The compiler treats the - sign differently when using an inline float versus a variable float.

History

#1 Updated by Charlie Somerville over 1 year ago

  • Status changed from Open to Rejected

=begin
The (({*})) operator has a higher precedence than unary minus, so your example is actually (({-(4.5 * 0.5)})).
=end

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