Bug #13104: mathn.rb affects Rational literals

• Status: Closed
• Priority: Normal
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -
• ruby -v: r57270
• Backport: 2.2: REQUIRED, 2.3: REQUIRED, 2.4: REQUIRED

[nobu (Nobuyoshi Nakada)]

Without mathn:

$ ruby -e 'p 1.0r'
(1/1)

With mathn:

$ ruby -rmathn -e 'p 1.0r'
1

Is this intentional?

https://github.com/ruby/ruby/compare/trunk...nobu:bug/rational-literal-mathn

[shyouhei (Shyouhei Urabe)]

We looked at this issue at yesterday's developer meeting.

The intension was not made clear, but we confirmed that mathn's global side-effects are the nature of that library. Maybe requiring it implies your willing to accept such surprising behaviour.

[nobu (Nobuyoshi Nakada)]

• Subject changed from math.rb affects Rational literals to mathn.rb affects Rational literals

Just "don't use math"?

[stomar (Marcus Stollsteimer)]

Seems to be triggered by ext/mathn/rational/rational.c and ext/mathn/complex/complex.c, which activate "canonicalization" in rational.c and complex.c.

$ ruby -r mathn/rational -e 'p Rational(2/1)'
2
$ ruby -r mathn/complex -e 'p Complex("3+0i")'
3

I suppose the reasoning behind the behavior was that in mathematics generally the simplest representation of a number is used, and n/1 = n.

But what are the plans for mathn anyway? -- It seems to be deprecated since 2.2 (#10169).

[naruse (Yui NARUSE)]

• Target version deleted (2.5)

mathn is out of scope from release engineering.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Assigned to Closed

mathn was removed in Ruby 2.5.