Re: What is considered an "advanced" topic in Python?

From	Gene Heskett <gheskett@wdtv.com>
Subject	Re: What is considered an "advanced" topic in Python?
Date	2015-06-01 23:30 -0400
References	<c03de3a7-3429-44a3-8241-5a7d81b9aefc@googlegroups.com> <201506010949.35134.gheskett@wdtv.com> <6vtpmap39im9c9lfom4mfsqfuljrceki1s@4ax.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.35.1433215846.13271.python-list@python.org> (permalink)

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On Monday 01 June 2015 20:33:50 Dennis Lee Bieber wrote:
> On Mon, 1 Jun 2015 09:49:35 -0400, Gene Heskett <gheskett@wdtv.com>
>
> declaimed the following:
> >But IMO, any language that does not have the ability to set an fp
> > number to a fixed number of digits to the right of the separator
> > regardless of which , or . is used, needs one written.
>
> 	That removes all modern hardware units using IEEE floating point
> standard, and pretty much all languages since (including) the first
> version of FORTRAN.
>
> 	Floating point numbers are x-significant digits (commonly x:7 for
> single precision and x:15 for double precision) with an exponent.
>
> 	Ada supports float and fixed point, but fixed point most easily
> visualized as an integer with a scaling factor.
>
> >The ability to guarantee that the output of a FIX(2) is zero to at
> > least 17 significant digits so that a zero coomparison is not
> > non-zero because theres a 1 15 digits out in a 2 digit money format,
> > is an absolute requirement.
>
> 	Use COBOL then... One used to have to go out of their way to get a
> "floating point" data type in COBOL... The common numeric type is
> packed BCD.
>
> 	Even M$ "money" datatype uses four decimal places even if only two
> are displayed to the user -- it allows for accumulation of fractions
> of a cent over time.
>
That is a far more restrictive interpretation than I had in mind.  What, 
in the case of g-code should be the result of looking at a double and 
seeing that rounding errors in incrementing a number origially set to 
zero adding 1.000 to it 21 times, have created say 21.00000001200873000. 
Then we do a 

while [number gt 0.000000]
number=number - 1.0000000
do stuff using that number
endwhile

But the loop then iterates an extra pass, because the 1200873000 is still 
there.  The numbers are all double's, but weren't initialized to a 
sufficient number of digits to the right of the . or ,

This is of course our own fault, caused by sloppy coding.  But specifying 
the value to 15 magnitudes more than the machine is capable of without 
spending weeks writing a screw compensation file to get that level of 
accuracy is counterproductive.  Its severe overkill IMO.  Any language 
ought to just throw away those rounding errors by filling the extra 
precision with NNNNN.nnnn000000000000000's. even if the original 
initialized value was only stated as 1.00000.


> --
> 	Wulfraed                 Dennis Lee Bieber         AF6VN
>     wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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What is considered an "advanced" topic in Python? Mike Driscoll <kyosohma@gmail.com> - 2015-05-29 09:01 -0700
  Re: What is considered an "advanced" topic in Python? Joel Goldstick <joel.goldstick@gmail.com> - 2015-05-29 12:08 -0400
    Re: What is considered an "advanced" topic in Python? Mike Driscoll <kyosohma@gmail.com> - 2015-05-29 09:55 -0700
  Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-05-30 02:09 +1000
    Re: What is considered an "advanced" topic in Python? Mike Driscoll <kyosohma@gmail.com> - 2015-05-29 09:57 -0700
      Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-05-30 03:08 +1000
      Re: What is considered an "advanced" topic in Python? random832@fastmail.us - 2015-05-31 23:18 -0400
      Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-06-01 13:43 +1000
      Re: What is considered an "advanced" topic in Python? Laura Creighton <lac@openend.se> - 2015-06-01 09:58 +0200
        Re: What is considered an "advanced" topic in Python? Marko Rauhamaa <marko@pacujo.net> - 2015-06-01 12:36 +0300
          Zero [was Re: What is considered an "advanced" topic in Python?] Steven D'Aprano <steve@pearwood.info> - 2015-06-01 22:07 +1000
            Re: Zero [was Re: What is considered an "advanced" topic in Python?] Laura Creighton <lac@openend.se> - 2015-06-01 14:52 +0200
            Re: Zero [was Re: What is considered an "advanced" topic in Python?] Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-06-01 13:56 +0100
              Re: Zero [was Re: What is considered an "advanced" topic in Python?] Skip Montanaro <skip.montanaro@gmail.com> - 2015-06-01 08:14 -0500
                Re: Zero [was Re: What is considered an "advanced" topic in Python?] Dave Farrance <df@see.replyto.invalid> - 2015-06-01 15:39 +0100
              Re: Zero [was Re: What is considered an "advanced" topic in Python?] Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-01 18:35 +0100
              Re: Zero [was Re: What is considered an "advanced" topic in Python?] Terry Reedy <tjreedy@udel.edu> - 2015-06-01 17:32 -0400
            Re: Zero [was Re: What is considered an "advanced" topic in Python?] Marko Rauhamaa <marko@pacujo.net> - 2015-06-01 16:18 +0300
              Re: Zero [was Re: What is considered an "advanced" topic in Python?] random832@fastmail.us - 2015-06-01 09:32 -0400
        Re: What is considered an "advanced" topic in Python? Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-06-01 11:44 +0100
          Re: What is considered an "advanced" topic in Python? Marko Rauhamaa <marko@pacujo.net> - 2015-06-01 13:54 +0300
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        Re: What is considered an "advanced" topic in Python? Marko Rauhamaa <marko@pacujo.net> - 2015-06-01 14:57 +0300
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          Re: What is considered an "advanced" topic in Python? Laura Creighton <lac@openend.se> - 2015-06-01 17:07 +0200
            Re: What is considered an "advanced" topic in Python? alister <alister.nospam.ware@ntlworld.com> - 2015-06-01 15:26 +0000
              Re: What is considered an "advanced" topic in Python? Laura Creighton <lac@openend.se> - 2015-06-01 17:51 +0200
              Re: What is considered an "advanced" topic in Python? MRAB <python@mrabarnett.plus.com> - 2015-06-01 18:06 +0100
                Re: What is considered an "advanced" topic in Python? Marko Rauhamaa <marko@pacujo.net> - 2015-06-01 20:14 +0300
            Re: What is considered an "advanced" topic in Python? BartC <bc@freeuk.com> - 2015-06-01 16:42 +0100
              Re: What is considered an "advanced" topic in Python? Grant Edwards <invalid@invalid.invalid> - 2015-06-01 17:02 +0000
                Re: What is considered an "advanced" topic in Python? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-01 18:45 +0100
                Re: What is considered an "advanced" topic in Python? Grant Edwards <invalid@invalid.invalid> - 2015-06-01 18:23 +0000
        Re: What is considered an "advanced" topic in Python? BartC <bc@freeuk.com> - 2015-06-01 13:24 +0100
      Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-06-01 23:52 +1000
        Re: What is considered an "advanced" topic in Python? BartC <bc@freeuk.com> - 2015-06-01 16:17 +0100
          Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-06-02 02:10 +1000
            Re: What is considered an "advanced" topic in Python? Rustom Mody <rustompmody@gmail.com> - 2015-06-01 21:46 -0700
  Re: What is considered an "advanced" topic in Python? Skip Montanaro <skip.montanaro@gmail.com> - 2015-05-29 11:39 -0500
    Re: What is considered an "advanced" topic in Python? Mike Driscoll <kyosohma@gmail.com> - 2015-05-29 09:58 -0700
  Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-05-30 02:50 +1000
  Re: What is considered an "advanced" topic in Python? Todd <toddrjen@gmail.com> - 2015-05-29 19:02 +0200
  Re: What is considered an "advanced" topic in Python? sohcahtoa82@gmail.com - 2015-05-29 10:03 -0700
    Re: What is considered an "advanced" topic in Python? Ethan Furman <ethan@stoneleaf.us> - 2015-05-29 10:17 -0700
      Re: What is considered an "advanced" topic in Python? sohcahtoa82@gmail.com - 2015-05-29 14:06 -0700
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        Re: What is considered an "advanced" topic in Python? Ethan Furman <ethan@stoneleaf.us> - 2015-05-29 14:44 -0700
    Re: What is considered an "advanced" topic in Python? Marko Rauhamaa <marko@pacujo.net> - 2015-05-29 20:24 +0300
  Re: What is considered an "advanced" topic in Python? Todd <toddrjen@gmail.com> - 2015-05-29 19:03 +0200
  Re: What is considered an "advanced" topic in Python? Steven D'Aprano <steve@pearwood.info> - 2015-05-30 03:55 +1000
    Re: What is considered an "advanced" topic in Python? Mike Driscoll <kyosohma@gmail.com> - 2015-05-29 13:38 -0700
  Re: What is considered an "advanced" topic in Python? Sturla Molden <sturla.molden@gmail.com> - 2015-05-30 12:15 +0000
  Re: What is considered an "advanced" topic in Python? jonathon <jonathon.blake@gmail.com> - 2015-05-30 19:32 +0000
  Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-05-31 08:24 +1000
  Re: What is considered an "advanced" topic in Python? "C.D. Reimer" <chris@cdreimer.com> - 2015-05-30 18:28 -0700
  Re: What is considered an "advanced" topic in Python? Rustom Mody <rustompmody@gmail.com> - 2015-05-30 20:30 -0700
    Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-05-31 14:25 +1000
      Re: What is considered an "advanced" topic in Python? Rustom Mody <rustompmody@gmail.com> - 2015-05-30 21:46 -0700
        Re: What is considered an "advanced" topic in Python? Chris Angelico <rosuav@gmail.com> - 2015-05-31 14:58 +1000
          Re: What is considered an "advanced" topic in Python? Rustom Mody <rustompmody@gmail.com> - 2015-05-30 22:18 -0700
  Re: What is considered an "advanced" topic in Python? Gene Heskett <gheskett@wdtv.com> - 2015-06-01 09:49 -0400
  Re: What is considered an "advanced" topic in Python? Denis McMahon <denismfmcmahon@gmail.com> - 2015-06-01 15:30 +0000
  Re: What is considered an "advanced" topic in Python? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-06-01 20:33 -0400
  Re: What is considered an "advanced" topic in Python? Gene Heskett <gheskett@wdtv.com> - 2015-06-01 23:30 -0400

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