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Groups > comp.lang.c > #91886

Re: Float Vs Double

From Real Troll <real.troll@trolls.com>
Newsgroups comp.lang.c
Subject Re: Float Vs Double
Date 2016-08-07 18:55 -0400
Organization Aioe.org NNTP Server
Message-ID <no8dgp$equ$1@gioia.aioe.org> (permalink)
References <no8ad8$ah6$1@gioia.aioe.org> <precision-20160807232513@ram.dialup.fu-berlin.de>

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So how do you perform scientific calculations which have to be as 
precise as possible?  what changes one has to make to get 22 or more 
decimal places (see the program I gave before).  To give you a trivial 
example, PI can be written as infinite decimal places so how do you 
accommodate this?


On 07/08/2016 23:26, Stefan Ram wrote:
> Real Troll <real.troll@trolls.com> writes:
>> Any reasons why the default precision value is still 6 since the bad old
>> days?  For example the result I get is this:
>    There is no »default precision value« in C. But FLT_DIG
>    indeed has to be at least 6. But since the type of a
>    floating constant, such as »1.0«, is »double« and not
>    »float«, the »default« is more something like »double« and
>    not »float«, and DBL_DIG has to be at least 10 (I believe
>    it usually is more some value near 15).
>
>    For many continuous values humans use, six digits already
>    are enough. For example, a temperature measured can be
>
> 33.3 degrees
>
>    , the speed of a car can be
>
> 20.2 m.p.h.
>
>    , the lenght of a rod of copper can be
>
> 15.2 mm
>
>    , but did you ever observe a temperature of
>
> 33.31321 degrees
>
>    , or a speed of
>
> 20.2214081 m.p.h.
>
>    , or a rod with a length or
>
> 15.211418 mm
>
>    ? Or can you prepare a temperature, a speed or a length
>    with such a precision?
>
>    So, for many cases, 6 digits already are sufficient and
>    15 are more than enough. And some implementations have
>    a long double type with even more precision.
>
>    When still more precision is needed, one can download a library,
>    in which case C++ with its operator overloading of course
>    would be nice.
>
>

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Float Vs Double Real Troll <real.troll@trolls.com> - 2016-08-07 17:59 -0400
  Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-07 23:38 +0100
  Re: Float Vs Double Real Troll <real.troll@trolls.com> - 2016-08-07 18:55 -0400
    Re: Float Vs Double jameskuyper@verizon.net - 2016-08-07 16:43 -0700
      Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-07 19:36 -0700
        Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-08 04:05 +0100
          Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-07 20:41 -0700
            Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-08 11:41 +0100
              Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-08 04:23 -0700
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-08 23:45 +0100
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-10 03:26 -0700
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-11 01:00 +0100
        Re: Float Vs Double jameskuyper@verizon.net - 2016-08-08 08:52 -0700
          Re: Float Vs Double James Kuyper <jameskuyper@verizon.net> - 2016-08-08 11:58 -0400
          Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-08 10:06 -0700
      Re: Float Vs Double "James R. Kuyper" <jameskuyper@verizon.net> - 2016-08-08 19:46 -0400
    Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-07 21:29 -0400
      Re: Float Vs Double jacobnavia <jacob@jacob.remcomp.fr> - 2016-08-08 14:04 +0200
        Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-08 09:00 -0400
          Re: Float Vs Double jacobnavia <jacob@jacob.remcomp.fr> - 2016-08-08 18:43 +0200
            Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-08 14:34 -0400
              Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-08 12:00 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-08 16:42 -0400
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-08 14:04 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-09 08:48 -0400
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-10 03:22 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-21 18:31 -0400
                Re: Float Vs Double supercat@casperkitty.com - 2016-08-22 08:39 -0700
                Re: Float Vs Double Jean-Marc Bourguet <jm@bourguet.org> - 2016-08-22 19:29 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-22 19:24 -0400
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-23 01:01 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-22 21:58 -0400
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-23 09:38 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 08:15 -0400
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-23 15:07 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 09:40 -0400
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-23 15:14 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 10:38 -0400
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-23 17:18 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 15:47 -0400
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-23 16:39 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 11:45 -0400
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-23 21:42 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 15:52 -0400
                Re: Float Vs Double Ian Collins <ian-news@hotmail.com> - 2016-08-24 08:36 +1200
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-24 09:39 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-24 11:31 -0400
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-23 10:48 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 08:17 -0400
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-23 06:01 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 09:44 -0400
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-23 07:19 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 10:39 -0400
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-23 08:18 -0700
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-23 14:47 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 10:40 -0400
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-24 01:31 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-23 20:53 -0400
                Re: Float Vs Double supercat@casperkitty.com - 2016-08-23 23:20 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-24 11:32 -0400
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-24 09:46 +0200
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-24 14:53 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-24 11:35 -0400
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-24 08:57 -0700
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-24 17:36 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-24 12:50 -0400
                Re: Float Vs Double Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-24 17:26 +0100
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-24 12:51 -0400
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-24 11:33 -0400
                Re: Float Vs Double Robert Wessel <robertwessel2@yahoo.com> - 2016-08-28 02:33 -0500
                Re: Float Vs Double antispam@math.uni.wroc.pl - 2016-08-31 22:36 +0000
                Re: Float Vs Double supercat@casperkitty.com - 2016-08-31 15:51 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-31 22:42 -0400
                Re: Float Vs Double supercat@casperkitty.com - 2016-09-01 08:32 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-01 15:00 -0400
                Re: Float Vs Double supercat@casperkitty.com - 2016-09-01 13:45 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-01 20:50 -0400
                Re: Float Vs Double supercat@casperkitty.com - 2016-09-02 08:11 -0700
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-02 12:25 -0400
                Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-09-02 20:42 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-02 16:25 -0400
                Re: Float Vs Double Jean-Marc Bourguet <jm@bourguet.org> - 2016-09-03 08:43 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-03 10:48 -0400
                Re: Float Vs Double Jean-Marc Bourguet <jm@bourguet.org> - 2016-09-03 19:43 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-03 18:16 -0400
                Re: Float Vs Double asetofsymbols@gmail.com - 2016-09-08 11:18 -0700
                Re: Float Vs Double Robert Wessel <robertwessel2@yahoo.com> - 2016-09-07 19:59 -0500
                Re: Float Vs Double supercat@casperkitty.com - 2016-09-08 08:13 -0700
                Re: Float Vs Double Robert Wessel <robertwessel2@yahoo.com> - 2016-09-08 19:34 -0500
                Re: Float Vs Double supercat@casperkitty.com - 2016-09-09 07:50 -0700
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-02 23:40 -0700
                Re: Float Vs Double Jean-Marc Bourguet <jm@bourguet.org> - 2016-09-03 09:06 +0200
                Re: Float Vs Double Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-03 10:52 -0400
                Re: Float Vs Double Rosario19 <Ros@invalid.invalid> - 2016-08-24 08:57 +0200
                Re: Float Vs Double Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-24 01:04 -0700
    Re: Float Vs Double Ike Naar <ike@iceland.freeshell.org> - 2016-08-08 06:44 +0000
      Re: Float Vs Double Keith Thompson <kst-u@mib.org> - 2016-08-08 00:16 -0700
        Re: Float Vs Double Richard Damon <Richard@Damon-Family.org> - 2016-08-08 23:29 -0400
    Re: Float Vs Double jacobnavia <jacob@jacob.remcomp.fr> - 2016-08-08 14:03 +0200
      Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-08 05:14 -0700
        Re: Float Vs Double BGB <cr88192@hotmail.com> - 2016-08-09 19:53 -0500
  Re: Float Vs Double "James R. Kuyper" <jameskuyper@verizon.net> - 2016-08-07 18:47 -0400
  Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-07 17:04 -0700
    Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-08 05:49 -0700
    Re: Float Vs Double Nobody <nobody@nowhere.invalid> - 2016-08-10 03:26 +0100
      Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-09 20:15 -0700
        Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-10 06:07 -0700
      Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-10 06:13 -0700
        Re: Float Vs Double David Brown <david.brown@hesbynett.no> - 2016-08-10 16:43 +0200
          Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-10 07:56 -0700
          Re: Float Vs Double supercat@casperkitty.com - 2016-08-10 08:39 -0700
            Re: Float Vs Double Keith Thompson <kst-u@mib.org> - 2016-08-10 09:56 -0700
              Re: Float Vs Double Keith Thompson <kst-u@mib.org> - 2016-08-10 10:04 -0700
                Re: Float Vs Double Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-11 07:08 -0700
                Re: Float Vs Double "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-08-11 07:15 -0700
                Re: Float Vs Double Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-12 08:11 -0700
              Re: Float Vs Double jacobnavia <jacob@jacob.remcomp.fr> - 2016-08-10 20:38 +0200
                Re: Float Vs Double Keith Thompson <kst-u@mib.org> - 2016-08-10 12:20 -0700
                Re: Float Vs Double supercat@casperkitty.com - 2016-08-10 12:17 -0700
                Re: Float Vs Double jacobnavia <jacob@jacob.remcomp.fr> - 2016-08-10 21:48 +0200
                Re: Float Vs Double Keith Thompson <kst-u@mib.org> - 2016-08-10 13:40 -0700
              Re: Float Vs Double Ian Collins <ian-news@hotmail.com> - 2016-08-12 08:01 +1200
          Re: Float Vs Double BGB <cr88192@hotmail.com> - 2016-08-10 15:00 -0500

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