Re: primitive instruction for programming

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.lang.c
Subject	Re: primitive instruction for programming
Date	2015-04-14 09:40 +0200
Organization	A noiseless patient Spider
Message-ID	<mgig8f$uhs$1@dont-email.me> (permalink)
References	<e2dba237-d8d7-4dc3-a977-2b28b7c1e386@googlegroups.com> <mgfudf$35b$1@dont-email.me> <mgh47h$n2j$1@dont-email.me>

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On 13/04/15 21:09, Bartc wrote:
> On 13/04/2015 09:24, Richard Heathfield wrote:
> 
>> You might find it instructive to attempt to rewrite the following
>> without resorting to non-goto diversions of control flow (such as
>> function calls):
>>
>> unsigned long f(unsigned long m, unsigned long n)
>> {
>>    return m == 0 ? n + 1 : n == 0 ? f(m - 1, 1) : f(m - 1, f(m, n - 1));
>> }
>>
> 
> Trickier than I expected:
> 

Did you not recognise the function?  It has turned up in this group
before - it's the Ackerman function, well-known for being a computable
function that is not primitive recursive and cannot be turned into a
simple loop.  You have to use recursion - or simulate it (as you did)
with explicit stacks.

Richard's idea was to give the OP a hard problem, to force him to cheat
- he said his G macro was sufficient to replicate /any/ control
structure, and it clearly is not.  You either have to use the additional
control structure of call/return (as the OP did), or introduce
additional data to track simulated recursion (as you did).

Thread

primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 00:56 -0700
  Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-13 09:24 +0100
    Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 01:59 -0700
      Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-13 10:32 +0100
        Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 02:53 -0700
          Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 11:04 +0100
          Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-13 14:10 +0200
            Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-20 14:27 -0700
              Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-20 15:12 -0700
                Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-21 00:17 +0100
                Re: primitive instruction for programming Emiliano Gomes Padilha <egpadilha@gmail.com> - 2015-04-22 11:07 -0700
              Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 09:04 +0200
                Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-21 03:02 -0500
                Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-21 01:34 -0700
                Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 11:34 +0200
                Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-21 11:48 +0100
                Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-21 13:10 +0200
                Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-21 10:53 +0100
    Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 20:09 +0100
      Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 12:48 -0700
      Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 09:40 +0200
        Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-14 11:24 +0100
          Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-14 05:39 -0500
          Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 13:29 +0200
  Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 10:59 +0100
    Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 03:28 -0700
      Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 03:33 -0700
        Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 03:59 -0700
          Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 04:23 -0700
      Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 11:36 +0100
        Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 04:26 -0700
          Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 12:41 +0100
            Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 06:26 -0700
              Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-13 15:33 +0200
                Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 06:44 -0700
                Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-13 16:30 +0200
                Re: primitive instruction for programming Ian Collins <ian-news@hotmail.com> - 2015-04-14 07:52 +1200
                Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 09:47 +0200
                Re: primitive instruction for programming raltbos@xs4all.nl (Richard Bos) - 2015-04-14 08:10 +0000
                Re: primitive instruction for programming David Brown <david.brown@hesbynett.no> - 2015-04-14 10:40 +0200
        Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-13 17:52 +0000
          Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-13 18:20 -0500
            Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-13 18:33 -0500
              Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-14 19:51 +0000
          Re: primitive instruction for programming Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-16 09:04 -0700
            Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-17 02:25 +0000
              Re: primitive instruction for programming Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-17 08:34 -0700
                Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-17 17:49 +0100
                Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-17 19:06 +0000
                Re: primitive instruction for programming Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-17 20:45 -0700
                Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-18 16:43 +0000
                Re: primitive instruction for programming Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-18 09:56 -0700
                Re: primitive instruction for programming Stephen Sprunk <stephen@sprunk.org> - 2015-04-17 17:52 -0500
                Re: primitive instruction for programming Morris Dovey <mrdovey@iedu.com> - 2015-04-17 18:02 -0500
                Re: primitive instruction for programming Stephen Sprunk <stephen@sprunk.org> - 2015-04-17 19:26 -0500
                Re: primitive instruction for programming Morris Dovey <mrdovey@iedu.com> - 2015-04-17 20:04 -0500
                Re: primitive instruction for programming Michael Angelo Ravera <maravera@prodigy.net> - 2015-04-19 14:59 -0700
                Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-20 00:19 +0100
                Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-20 02:06 +0100
                Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-20 02:26 +0100
                Re: primitive instruction for programming Richard Heathfield <rjh@cpax.org.uk> - 2015-04-20 02:18 +0100
              Re: primitive instruction for programming Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-18 18:59 -0700
                Re: primitive instruction for programming Steve Thompson <stevet810@gmail.com> - 2015-04-19 16:28 +0000
                Re: primitive instruction for programming Richard Damon <Richard@Damon-Family.org> - 2015-04-19 17:16 -0400
                Re: primitive instruction for programming Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-22 15:28 -0700
          Re: primitive instruction for programming John Bode <jfbode1029@gmail.com> - 2015-04-23 07:20 -0700
  Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 03:07 -0700
    Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 09:47 -0700
      Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 11:09 -0700
        Re: primitive instruction for programming Noob <root@127.0.0.1> - 2015-04-13 20:43 +0200
          Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 12:09 -0700
            Re: primitive instruction for programming Xcott Craver <xcottcraver@gmail.com> - 2015-04-14 07:11 -0700
              Re: primitive instruction for programming fmassei@gmail.com - 2015-04-14 07:28 -0700
                Re: primitive instruction for programming Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-04-14 15:57 +0100
                Re: primitive instruction for programming fmassei@gmail.com - 2015-04-14 08:13 -0700
      Re: primitive instruction for programming fir <profesor.fir@gmail.com> - 2015-04-13 14:02 -0700
        Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 14:28 -0700
          Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 22:51 +0100
            Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 14:58 -0700
              Re: primitive instruction for programming Bartc <bc@freeuk.com> - 2015-04-13 23:25 +0100
                Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 15:37 -0700
                Re: primitive instruction for programming James Kuyper <jameskuyper@verizon.net> - 2015-04-13 19:09 -0400
                Re: primitive instruction for programming fmassei@gmail.com - 2015-04-13 16:20 -0700
                Re: primitive instruction for programming Robert Wessel <robertwessel2@yahoo.com> - 2015-04-13 18:03 -0500
            Re: primitive instruction for programming asetofsymbols@gmail.com - 2015-04-13 20:58 -0700
          Re: primitive instruction for programming fir <profesor.fir@gmail.com> - 2015-04-13 15:02 -0700

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