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From: "Lennart Borgman (gmail)" <lennart.borgman@gmail.com>
To: "Randal L. Schwartz" <merlyn@stonehenge.com>
Cc: emacs-devel@gnu.org
Subject: Re: In CVS Emacs, calc-eval gives multiplication higher  precidence than division
Date: Mon, 08 Sep 2008 09:26:59 +0200	[thread overview]
Message-ID: <48C4D3C3.60306@gmail.com> (raw)
In-Reply-To: <86y7231ltv.fsf@blue.stonehenge.com>

Randal L. Schwartz wrote:
> That's crazy.
> 
> That's (2b)/(5d), according to any math teacher I knew from school.
> 
> That's the only sane parsing of that.
> 
> Now, replace 2 with "a" and 5 with "c", and you get:
> 
>   ab/cd
> 
> which is (ab)/(cd).
> 
> That's what I mean. This is the *mathematical* evaluation.  In this case,
> division *is* lower precedence than multiplication.

I am afraid I think you misunderstand this issue. We are talking about

  a * b / c * d

But thanks, maybe I can understand a bit better why some people believe
that these precedence rules exists now. Indeed, as you pointed out "2b"
is often interpreted as "2 * b" and that might give the impression that
there is a precedence rule for * and / that says * has higher precedence.

But there is no such rule. It is about different notations instead.

You have to be more careful when translating notations. The notation
translation is rather

  2b / 5d => (2 * b) / (5 * d)




  parent reply	other threads:[~2008-09-08  7:26 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-07 16:06 In CVS Emacs, calc-eval gives multiplication higher precidence than division Francis Litterio
2008-09-07 16:37 ` Jay Belanger
2008-09-07 18:15   ` Francis Litterio
2008-09-07 19:46   ` Stefan Monnier
2008-09-07 20:19     ` bug#920: " Lennart Borgman (gmail)
2008-09-07 20:32     ` Randal L. Schwartz
2008-09-07 20:34       ` Lennart Borgman (gmail)
2008-09-07 20:38         ` Randal L. Schwartz
2008-09-07 20:42           ` Lennart Borgman (gmail)
2008-09-07 20:50             ` Randal L. Schwartz
2008-09-07 21:07               ` Lennart Borgman (gmail)
2008-09-08  6:39                 ` Ulrich Mueller
2008-09-08  7:07                   ` Lennart Borgman (gmail)
2008-09-07 21:10               ` Stefan Monnier
2008-09-07 23:30                 ` Jay Belanger
2008-09-08  0:50               ` Jason Rumney
2008-09-08  1:13             ` Randal L. Schwartz
2008-09-08  3:47               ` Stefan Monnier
2008-09-08  8:48                 ` Miles Bader
2008-09-08 12:59                   ` Stefan Monnier
2008-09-08 13:29                   ` martin rudalics
2008-09-08  7:26               ` Lennart Borgman (gmail) [this message]
2008-09-07 21:10           ` Stefan Monnier
2008-09-08 10:30       ` Carsten Dominik
2008-09-08 11:01         ` Lennart Borgman
2008-09-08 20:33           ` Carsten Dominik
2008-09-08 20:39             ` Lennart Borgman (gmail)
2008-09-08 20:43               ` Randal L. Schwartz
2008-09-08 20:53                 ` Lennart Borgman (gmail)
2008-09-08 22:59                   ` bug#914: " Jay Belanger
2008-09-08 23:44                     ` Lennart Borgman (gmail)
2008-09-09 13:28                     ` Stefan Monnier
2008-09-09 14:36                       ` Francis Litterio
2008-09-09 16:26                         ` Ulrich Mueller
2008-09-09 16:41                           ` Lennart Borgman (gmail)
2008-09-30  4:10                         ` Leo
2008-09-08 20:53                 ` Lennart Borgman (gmail)
2008-09-08 21:42                 ` Stefan Monnier
2008-09-09  8:11                 ` Richard M. Stallman
2008-09-09 13:26                   ` Stefan Monnier
2008-09-09 17:03                     ` Lennart Borgman (gmail)
2008-09-09 17:19                       ` Stefan Monnier
2008-09-08 13:01         ` Stefan Monnier
2008-09-07 20:35     ` Jay Belanger
2008-09-07 21:15       ` Stefan Monnier
2008-09-07 21:19         ` Lennart Borgman (gmail)

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