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Re: MISRA C

From bart <bc@freeuk.com>
Newsgroups comp.lang.c
Subject Re: MISRA C
Date 2026-09-25 16:57 +0100
Organization A noiseless patient Spider
Message-ID <11965kn$3nke3$1@dont-email.me> (permalink)
References (11 earlier) <1195gqh$23uj$1@news.muc.de> <1195qr8$2aem2$1@dont-email.me> <1195u2r$16ah$1@news.muc.de> <119612d$2aem2$2@dont-email.me> <11962u0$16ah$2@news.muc.de>

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On 25/09/2026 16:10, Alan Mackenzie wrote:
> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
>> On 2026-09-25 15:48, Alan Mackenzie wrote:
>>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
> 
> [ .... ]
> 
>>>> WRT Dude's statement it should be mentioned that a recursive algorithm
>>>> can be transformed to an iterative one, so if iterative algorithms
>>>> would have the property to be _decidable_ to finish - actually, they
>>>> are not - we could also say the same for a recursive one.
> 
>>> Recursion can often be programmed iteratively in practice.  In theory,
>>> there are recursively defined functions which grow too quickly with
>>> increasing argument to be definable (or programmable) without recursion.
> 
>> Have you functions like fib() in mind? - Despite they are cascaded
>> recursion you can create iterative ones. - But it's simpler; just
>> recognize that a recursion is using an implicit stack, so you can
>> write it in iterative form with an explicit stack. Even an extreme
>> function like Ackermann (which is more demanding) is not exempt to
>> that principle. - Or do you disagree? (Then please explain - best
>> with an example you may have in mind.)
> 
> Yes, it was the Ackermann function I had in mind (though I'd forgotten
> its name).  It's a function of two natural number arguments.  Simply
> making both arguments the same gives a function of one argument.
> 
> If memory serves me correctly (which it probably doesn't),
> A(0, 0) = 0.
> A(1, 1) = 1.
> A(2, 2) = 5.
> A(3, 3) = 63.

I think those last two should be 7 and 61.

> A(4, 4) = 2^2^2^2^2^2^2 + 3

If correct, that value would be:

   (2 ** 2 ** 2003...6736) + 3

That third number has over 19000 digits. I think it is equivalent to this:

   (2 ** X)

where X has about 2**2003...6736/3 digits.

The size of the stack might then be the smaller issue! But then, the 
stack needs to be tens of thousands deep just to do A(3, 10) where the 
numbers involved are small.

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MISRA C (was: buckle-up ....) Alan Mackenzie <acm@muc.de> - 2026-09-25 10:01 +0000
  Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-25 14:52 +0200
    Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-25 13:48 +0000
      Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-25 16:39 +0200
        Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-25 15:10 +0000
          Re: MISRA C bart <bc@freeuk.com> - 2026-09-25 16:57 +0100
          Re: MISRA C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-09-25 11:42 -0700
            Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-25 20:21 +0000
              Re: MISRA C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-09-25 14:05 -0700
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-09-26 08:43 +0200
                Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-26 17:55 +0000
                Re: MISRA C Ben Bacarisse <ben@bsb.me.uk> - 2026-10-03 23:55 +0100
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-10-04 16:10 +0200
                Re: MISRA C Ben Bacarisse <ben@bsb.me.uk> - 2026-10-05 01:22 +0100
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-10-05 07:59 +0200
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-05 01:23 -0700
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-05 01:24 -0700
                Re: MISRA C antispam@fricas.org (Waldek Hebisch) - 2026-10-05 09:02 +0000
                Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-05 12:07 +0200
                Re: MISRA C Ben Bacarisse <ben@bsb.me.uk> - 2026-10-05 15:29 +0100
                Re: MISRA C antispam@fricas.org (Waldek Hebisch) - 2026-10-05 20:29 +0000
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-06 22:13 -0700
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-06 22:14 -0700
          Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-09-27 10:52 -0700
          Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 13:08 +0200
            Re: MISRA C bart <bc@freeuk.com> - 2026-09-28 13:07 +0100
            Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-09-28 14:08 +0200
              Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 14:28 +0200
            Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-28 12:17 +0000
              Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 14:40 +0200
          Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-30 10:21 -0700
            Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-30 19:57 +0000
              Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-30 13:09 -0700
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-10-01 08:47 +0200
                Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-01 15:18 -0700
      Re: MISRA C Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-09-27 04:58 +0800
  Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-09-25 17:02 +0200
  Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-26 15:37 -0700

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