Issue #3289 has been updated by Alexey Muranov.

I think that both operations have right to exist. Maybe one of them should be denoted '/' and the other 'div'. For example: '/' rounds towards 0 and thus is symmetric with respect to exchanging x and -x, and 'div' returns the quotient and remainder in the "integral" sense (quotient being rounded towards -\infty).
-Alexey.
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Feature #3289: Division of negative numbers
http://redmine.ruby-lang.org/issues/3289

Author: Patrick Thomson
Status: Assigned
Priority: Low
Assignee: Yukihiro Matsumoto
Category: core
Target version:

=begin
The documentation for Numeric (http://www.ruby-doc.org/core/classes/Numeric.html#M000179) states that integer divmod() (and, by extension, /) rounds the quotient towards negative infinity. Python and Tcl behave similarly, while C, Java, bc, and gdb round the quotient towards zero, as is taught in standard arithmetic courses.

Is this a quirk of MRI's implementation, or is it desired Ruby behavior? If so, why?
It's counterintuitive that (-x/y) ¡â -(x/y), and even moreso when (-x/y) = -(x/y) if x or y is a non-integer.
=end

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