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Re: The problem with implementation defined behaviour.

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.lang.forth
Subject Re: The problem with implementation defined behaviour.
Date 2016-03-30 07:44 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2016Mar30.094455@mips.complang.tuwien.ac.at> (permalink)
References <56fa93aa$0$5868$e4fe514c@news.xs4all.nl> <2016Mar29.182032@mips.complang.tuwien.ac.at> <n9-dnSdCKI4ASWfLnZ2dnUU7-InNnZ2d@supernews.com>

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"Elizabeth D. Rather" <erather@forth.com> writes:
>On 3/29/16 6:20 AM, Anton Ertl wrote:
>> Albert van der Horst <albert@spenarnc.xs4all.nl> writes:
>>> I have this package that calculates modulo a VARIABLE _m.
>>> : +m   + _m @ MOD ;
>>> *m -m /m
>>> etc.
...
>A signed MOD makes no real-world sense. No one 
>has ever presented a mathematical argument for having a signed MOD that 
>I know of.

I thought about recommending to use UM/MOD for the problem outlined
above, but then found a case where negative dividends occur:

: -m - _m @ MOD ;

E.g., if you do 1 2 -M, the dividend is negative, so unsigned MOD
won't cut it here.

However, most people seem to only divide positive numbers by positive
numbers, as evidenced by the complete lack of complaints from users
when Gforth switched from symmetric to floored.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2015: http://www.rigwit.co.uk/EuroForth2015/

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The problem with implementation defined behaviour. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-29 14:39 +0000
  Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-29 16:20 +0000
    Re: The problem with implementation defined behaviour. "Elizabeth D. Rather" <erather@forth.com> - 2016-03-29 09:16 -1000
      Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-30 00:06 +0000
        Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-03-29 22:09 -0700
          Re: The problem with implementation defined behaviour. "Elizabeth D. Rather" <erather@forth.com> - 2016-03-29 21:37 -1000
          Re: The problem with implementation defined behaviour. Paul Rubin <no.email@nospam.invalid> - 2016-03-30 00:48 -0700
            Re: The problem with implementation defined behaviour. Paul Rubin <no.email@nospam.invalid> - 2016-03-30 00:48 -0700
          Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-30 07:59 +0000
            Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-03-30 10:16 -0700
              Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-30 23:43 +0000
                Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-03-31 06:01 -0700
                Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-01 21:36 +0000
                Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-04-01 14:57 -0700
                Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-01 21:59 +0000
                Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-04-02 00:51 -0700
                Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-01 08:25 +0000
                Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-01 21:32 +0000
                division performance (was: The problem with implementation defined ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-05 11:12 +0000
                Re: division performance (was: The problem with implementation defined ...) Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-05 20:45 +0000
                Re: division performance (was: The problem with implementation defined ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-06 10:03 +0000
                Re: division performance (was: The problem with implementation defined ...) Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-08 22:53 +0000
                Re: division performance (was: The problem with implementation defined ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-09 10:14 +0000
                Re: division performance (was: The problem with implementation defined ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-09 13:43 +0000
              Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-31 10:55 +0000
                Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-03-31 06:38 -0700
                Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-31 16:21 +0000
                Re: The problem with implementation defined behaviour. Paul Rubin <no.email@nospam.invalid> - 2016-03-31 11:49 -0700
                Re: The problem with implementation defined behaviour. "Elizabeth D. Rather" <erather@forth.com> - 2016-03-31 10:11 -1000
                Re: The problem with implementation defined behaviour. mhx@iae.nl - 2016-04-01 03:53 -0700
                Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-01 11:44 +0000
                Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-01 21:53 +0000
                Re: The problem with implementation defined behaviour. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-04-02 11:46 -0500
                Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-02 21:43 +0000
                Re: The problem with implementation defined behaviour. Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-04-03 03:17 -0500
                Re: The problem with implementation defined behaviour. hughaguilar96@gmail.com - 2016-04-01 23:54 -0700
          Re: The problem with implementation defined behaviour. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-30 12:58 +0000
          Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-30 22:22 +0000
        Re: The problem with implementation defined behaviour. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-30 12:55 +0000
      Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-30 07:44 +0000
        Re: The problem with implementation defined behaviour. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-30 13:08 +0000
          Re: The problem with implementation defined behaviour. anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-03-30 13:43 +0000
        Re: The problem with implementation defined behaviour. Bernd Paysan <bernd.paysan@gmx.de> - 2016-03-30 22:06 +0000
      Re: The problem with implementation defined behaviour. trevor <tgritchie@blueyonder.co.uk> - 2016-03-30 13:13 +0100
        Re: The problem with implementation defined behaviour. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-30 13:56 +0000
      Re: The problem with implementation defined behaviour. Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-03-30 12:49 +0000

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