[#9382] the sign of a number is omitted when squaring it. -2**2 vs (-2)**2 — <noreply@...>

Bugs item #6468, was opened at 2006-11-03 17:25

9 messages 2006/11/03

[#9385] merge YARV into Ruby — SASADA Koichi <ko1@...>

Hi,

42 messages 2006/11/04
[#9405] Re: merge YARV into Ruby — "Kirill Shutemov" <k.shutemov@...> 2006/11/06

On 11/4/06, SASADA Koichi <ko1@atdot.net> wrote:

[#9406] Re: merge YARV into Ruby — Sylvain Joyeux <sylvain.joyeux@...4x.org> 2006/11/06

On Monday 06 November 2006 16:01, Kirill Shutemov wrote:

[#9417] Re: merge YARV into Ruby — Sean Russell <ser@...> 2006/11/06

On Monday 06 November 2006 10:15, Sylvain Joyeux wrote:

[#9428] Re: merge YARV into Ruby — "Kirill Shutemov" <k.shutemov@...> 2006/11/06

On 11/6/06, Sean Russell <ser@germane-software.com> wrote:

[#9402] fast mutexes for 1.8? — MenTaLguY <mental@...>

Many people have been using Thread.critical for locking because Ruby

24 messages 2006/11/06

[#9450] Bikeshed: No more Symbol < String? — Kornelius Kalnbach <murphy@...>

Hi ruby-core!

21 messages 2006/11/07
[#9452] Re: Bikeshed: No more Symbol < String? — Yukihiro Matsumoto <matz@...> 2006/11/07

Hi,

[#9493] Future Plans for Ruby 1.8 Series — URABE Shyouhei <shyouhei@...>

This week Japanese rubyists were talking about the future of ruby_1_8

13 messages 2006/11/09

[#9515] External entropy pool for random number generator — "Kirill Shutemov" <k.shutemov@...>

In the attachment patch which allow to use external entropy pool for

13 messages 2006/11/11
[#9522] Re: External entropy pool for random number generator — "Nobuyoshi Nakada" <nobu@...> 2006/11/13

Hi,

[#9554] Ruby 1.[89].\d+ and beyond. — Hugh Sasse <hgs@...>

I've been thinking about how version numbers are restricting what we can do.

30 messages 2006/11/16
[#9561] Re: Ruby 1.[89].\d+ and beyond. — Eric Hodel <drbrain@...7.net> 2006/11/16

[#9563] Re: Ruby 1.[89].\d+ and beyond. — Hugh Sasse <hgs@...> 2006/11/16

On Fri, 17 Nov 2006, Eric Hodel wrote:

[#9564] Re: Ruby 1.[89].\d+ and beyond. — Eric Hodel <drbrain@...7.net> 2006/11/16

On Nov 16, 2006, at 12:02 PM, Hugh Sasse wrote:

[#9571] Re: Ruby 1.[89].\d+ and beyond. — "Robert Dober" <robert.dober@...> 2006/11/19

On 11/16/06, Eric Hodel <drbrain@segment7.net> wrote:

[#9604] #ancestors never includes the singleton class (inconsistent) — <noreply@...>

Bugs item #6820, was opened at 2006-11-22 08:49

12 messages 2006/11/22
[#9618] Re: [ ruby-Bugs-6820 ] #ancestors never includes the singleton class (inconsistent) — Yukihiro Matsumoto <matz@...> 2006/11/25

Hi,

[#9629] Re: [ ruby-Bugs-6820 ] #ancestors never includes the singleton class (inconsistent) — Sylvain Joyeux <sylvain.joyeux@...4x.org> 2006/11/27

> It is supposed to. Singleton classes (or eigenclasses, if you want to

Re: [ ruby-Bugs-6468 ] the sign of a number is omitted when squaring it. -2**2 vs (-2)**2

From: Joel VanderWerf <vjoel@...>
Date: 2006-11-05 19:21:45 UTC
List: ruby-core #9397
Yukihiro Matsumoto wrote:
> Hi,
> 
> In message "Re: [ ruby-Bugs-6468 ] the sign of a number is omitted when squaring it. -2**2 vs (-2)**2"
>     on Sun, 5 Nov 2006 04:23:30 +0900, Joel VanderWerf <vjoel@path.berkeley.edu> writes:
> 
> |Any yet
> |
> |irb(main):002:0> -2.abs
> |=> 2
> |
> |So there are cases where the operation of "concatenating characters to 
> |form a literal" has higher priority than an operation on objects.
> 
> People with mathematical background demands precedence for ** being
> higher than that of unary minus.  That's the reason.

Precedence isn't the whole story:

irb(main):001:0> x=2
=> 2
irb(main):002:0> -x**2
=> -4
irb(main):003:0> -2**2
=> -4
irb(main):004:0> -x.abs
=> -2
irb(main):005:0> -2.abs
=> 2

Tokenization works differently in different contexts (as it should). 
Mathematicians need to learn this, when they read line 005 above.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407

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