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Re: In CVS Emacs, calc-eval gives multiplication higher precidence than
From: |
Randal L. Schwartz |
Subject: |
Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division |
Date: |
Sun, 07 Sep 2008 18:13:32 -0700 |
User-agent: |
Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (berkeley-unix) |
>>>>> "Lennart" == Lennart Borgman (gmail) <address@hidden> writes:
Lennart> More seriously: Where do you get those rules from? The notation
Lennart> a b / c d
Lennart> does not look like a standard math notation.
If a is 2, and c is 5, you're actually telling me that *you*
would parse:
2 b / 5 d
as ((2 * b) / 5) * d ?
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.
Anyway, maybe you've never seen expressions like 2a/5d before. I dealt with
them in my algebra class, but perhaps that was before you were born, and
before computers came into usage in high schools. I suppose the rules changed
once we started teaching * and / as same precedence in computer science, which
then leaked over into math notation as well.
I'm probably not going to convince you of anything here, but I did want to
come up with a better example, now that I'm going through the calc manual
again. And then, it made perfect sense, as it still does.
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<address@hidden> <URL:http://www.stonehenge.com/merlyn/>
Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
See http://methodsandmessages.vox.com/ for Smalltalk and Seaside discussion
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, (continued)
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman (gmail), 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Randal L. Schwartz, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman (gmail), 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Randal L. Schwartz, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman (gmail), 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Ulrich Mueller, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman (gmail), 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Stefan Monnier, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Jay Belanger, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Jason Rumney, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division,
Randal L. Schwartz <=
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Stefan Monnier, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Miles Bader, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Stefan Monnier, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, martin rudalics, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman (gmail), 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Stefan Monnier, 2008/09/07
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Carsten Dominik, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Carsten Dominik, 2008/09/08
- Re: In CVS Emacs, calc-eval gives multiplication higher precidence than division, Lennart Borgman (gmail), 2008/09/08