Re: A little puzzle.

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From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.programming
Subject	Re: A little puzzle.
Date	Tue, 29 Nov 2022 04:29:42 -0800
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Julio Di Egidio <julio@diegidio.name> writes:

> On Monday, 28 November 2022 at 16:22:38 UTC+1, Tim Rentsch wrote:
>
>> Julio Di Egidio <an unrepentant google groups user> writes:
>>
>>>>> On Monday, 21 November 2022 at 21:45:34 UTC+1, Ben Bacarisse wrote:

[...]

>>>>>> Consider any ordered measure that "wraps round" -- bearings in
>>>>>> degrees, minutes in the hour, indeed hours in either the 12 or
>>>>>> 24 hour clock.  The problem is to determine if a given value is
>>>>>> in the sub-range specified by a start and an en value.
>>>
>>> Argh!  But you should not have snipped that "beware
>>> of bugs", that was the most important part!! ;)
>>
>> It's your job to beware of bugs, not mine.
>
> I didn't know you were paying me for production level code:

You are under no obligation to post bug-free code.  Similarly I
am under no obligation to correct bugs in your code.  But if you
want your postings to be taken seriously it's important to put
more thought into what is posted and make an effort to avoid
careless mistakes.

> in that case, I'd have asked for the technical requirements,
> not just the functional ones...
>
> IOW, I have have given a mathematical spec written in some
> simply-typed functional language, can be functions on the real
> numbers.  Which is often step one in functional/algorithmic
> design.  Beside that point, one needs technical requirements,
> i.e. info on the concrete numeric types available as a minimum.

Part of the challenge is to figure out what the interface should
be.  The problem is not just a coding exercise.

>>> This one should do the trick:
>>>
>>> ```ts
>>> /** Returns whether x in [lo, hi[ (mod m). */
>>> function inOpenModRange(
>>> x:  number, lo:  number, hi:  number, m:  number
>>> ): boolean {
>>> let x_ = MOD(x - lo, m);
>>> let hi_ = MOD(hi - lo, m);
>>> return x_ < hi_;
>>> }
>>> ```
>>
>> This scheme looks like it will work, as long as the values given
>> don't get too near the edges of representation.  JavaScript
>> represents numeric values using floating point, and that choice
>> leads to some unexpected results when working with large numbers.
>>
>> However, this approach is more complicated than it needs to be.
>> Have you tried looking at the other answers?
>
> That is complicated??  Maybe I haven't looked well enough
> but, honestly, I have not seen anything that is even vaguely as
> clear, and efficient, and to the point.  Have I missed it?

The question can be answered without using any of subtraction,
remainder, or mod, and more than one solution has been posted
demonstrating that property.  Perhaps you missed those answers.

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A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-21 20:45 +0000
  Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-21 22:06 +0100
    Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-21 21:21 +0000
      Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-22 09:17 +0100
        Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-22 11:07 +0000
          Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-22 15:17 +0100
        Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-22 11:40 +0000
          Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-22 15:26 +0100
            Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-22 15:28 +0000
              Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-22 16:30 +0100
      Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-22 09:23 +0100
        Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-22 11:08 +0000
        Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-22 12:54 +0000
  Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-21 17:39 -0800
    Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-22 13:00 +0000
      Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-22 05:31 -0800
  Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-22 11:04 +0000
    Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-22 12:53 +0000
      Re: A little puzzle. Paul N <gw7rib@aol.com> - 2022-11-22 05:01 -0800
        Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-22 05:48 -0800
          Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-22 15:31 +0100
      FFs [was Re: A little puzzle] Richard Harnden <richard.nospam@gmail.com> - 2022-11-22 16:29 +0000
    Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-12-14 13:57 +0000
      Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-12-14 13:58 +0000
      Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-12-14 16:22 +0000
  Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-22 05:24 -0800
    Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-22 15:23 +0000
      Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-23 08:04 -0800
        Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-24 00:06 +0000
          Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-24 04:06 +0000
            Re: A little puzzle. David Brown <david.brown@hesbynett.no> - 2022-11-24 09:29 +0100
              Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-24 13:23 +0000
            Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-24 13:14 +0000
              Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-24 14:00 +0000
                Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-24 14:59 +0000
                Re: A little puzzle. Richard Harnden <richard.nospam@gmail.com> - 2022-11-24 19:00 +0000
                Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-24 20:36 +0000
              Re: A little puzzle. Andreas <nobody@me.com> - 2022-11-27 00:38 +0100
                Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-27 00:11 +0000
          Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-24 14:51 -0800
            Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-25 09:30 +0100
              Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-25 01:16 -0800
                Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-25 11:11 +0100
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-25 06:26 -0800
                Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-25 15:59 +0100
            Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-26 16:25 +0000
              Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-26 19:36 +0100
                Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-27 02:03 +0000
                Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-27 11:02 +0100
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-01 04:30 -0800
                Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-12-02 00:22 +0000
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-02 22:30 -0800
                Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-12-03 02:43 -0800
              Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-27 18:38 -0800
  Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-27 02:27 -0800
    Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-27 19:23 -0800
      Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-27 22:59 -0800
        Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-27 23:03 -0800
        Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-28 07:22 -0800
          Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-28 10:20 -0800
            Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-29 04:29 -0800
              Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-29 04:50 -0800
                Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-29 14:47 +0000
                Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-29 17:23 +0000
                Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-29 09:50 -0800
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-30 01:39 -0800
                Re: A little puzzle. Richard Heathfield <rjh@cpax.org.uk> - 2022-11-30 11:10 +0000
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-30 02:24 -0800
                Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-30 06:28 -0800
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-01 06:55 -0800
                Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-12-02 01:54 -0800
  Re: A little puzzle. Richard Harnden <richard.nospam@gmail.com> - 2022-11-28 11:20 +0000
    Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-28 07:30 -0800
      Re: A little puzzle. Richard Harnden <richard.nospam@gmail.com> - 2022-11-28 17:15 +0000
        Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-29 04:03 -0800
          Re: A little puzzle. Richard Harnden <richard.nospam@gmail.com> - 2022-11-29 15:03 +0000
            Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-29 16:13 +0100
              Re: A little puzzle. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-29 17:37 +0000
                Re: A little puzzle. "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> - 2022-11-29 19:02 +0100
                Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-29 10:10 -0800
            Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-30 03:32 -0800
              Re: A little puzzle. Julio Di Egidio <julio@diegidio.name> - 2022-11-30 06:36 -0800
              Re: A little puzzle. Richard Harnden <richard.nospam@gmail.com> - 2022-11-30 15:21 +0000
                Re: A little puzzle. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-01 06:51 -0800

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