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Groups > comp.lang.c > #66832

Re: routine for angles needed

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: routine for angles needed
Date 2015-08-03 18:33 -0700
Organization None to speak of
Message-ID <lnlhdrhm6r.fsf@kst-u.example.com> (permalink)
References (7 earlier) <ca0e8c9e-cff4-431c-aab9-65a4b29e2435@googlegroups.com> <mpo5tl$2kj$1@dont-email.me> <lntwsggkzc.fsf@kst-u.example.com> <mposep$bvs$1@speranza.aioe.org> <mpp143$dvl$1@dont-email.me>

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Bartc <bc@freeuk.com> writes:
> On 04/08/2015 00:11, glen herrmannsfeldt wrote:
>> Keith Thompson <kst-u@mib.org> wrote:
>>> Bartc <bc@freeuk.com> writes:
>>> [...]
>>>> C uses binary floating point.
>>> [...]
>>
>>> Most (probably nearly all) C implementations use binary floating-point.
>>> The standard permits other bases, which is why FLT_RADIX exists.
>>
>> I believe there are, or have been, some that are radix 8.
>>
>> IBM S/360 and descendants use 16. Rumors are that it was Java that
>> cause them to add IEEE binary to ESA/390, (now called BFP for binary
>> floating point, the previous one now called HFP).
>
> What does it actually mean that floating point format uses radix 8 or 16?

It means that the exponent part of the floating-point representation is
a power of 16 (or 8) rather than of 2.

You can represent a wider range of numbers using the same number of
exponent bits, but at the expense of some loss of precision for some
values.

With binary floating-point, the difference between consecutive
representable numbers jumps by a factor of 2 every time the exponent
value changes.  With hexadecimal, it jumps by a factor of 16.

> If someone decided to take an 8-bit byte type and implement it as 2 hex 
> digits instead, but difference would it make? I'd imagine that shifts 
> would work differently: a 1 digit shift in hex is the same as a 4-bit 
> shift in binary; anything else?
>
> Does floating point in radix 16 solve the problem of representing 0.1?

No.  Why would it?

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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Thread

routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 10:17 -0700
  Re: routine for angles needed Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-02 10:38 -0700
    Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 11:10 -0700
      Re: routine for angles needed Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-02 11:26 -0700
        Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 11:41 -0700
          Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:02 -0700
  Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-02 18:41 +0100
    Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 11:43 -0700
      Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-02 20:00 +0100
        Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:04 -0700
          Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:10 -0700
            Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:24 -0700
              Re: routine for angles needed Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-02 12:32 -0700
                Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-02 20:40 +0100
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:59 -0700
                Re: routine for angles needed Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-02 13:14 -0700
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 13:39 -0700
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 13:45 -0700
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-03 07:48 -0700
                Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-03 17:06 +0100
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-03 09:09 -0700
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-03 09:17 -0700
                Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-03 17:48 +0100
                Re: routine for angles needed Keith Thompson <kst-u@mib.org> - 2015-08-03 13:44 -0700
                Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-03 23:51 +0100
                Re: routine for angles needed Keith Thompson <kst-u@mib.org> - 2015-08-03 18:30 -0700
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-03 23:11 +0000
                Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-04 01:32 +0100
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-04 01:14 +0000
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-08-03 20:26 -0500
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-04 18:24 +0000
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-08-05 01:46 -0500
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-05 18:06 +0000
                Re: routine for angles needed Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-05 11:37 -0700
                Re: routine for angles needed Keith Thompson <kst-u@mib.org> - 2015-09-05 16:24 -0700
                Re: routine for angles needed Richard Damon <Richard@Damon-Family.org> - 2015-09-05 21:01 -0400
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-09-05 23:30 -0500
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-06 05:37 +0000
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-09-07 00:27 -0500
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-06 05:31 +0000
                Re: routine for angles needed James Kuyper <jameskuyper@verizon.net> - 2015-09-06 11:57 -0400
                Re: routine for angles needed Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-06 17:44 +0100
                Re: routine for angles needed James Kuyper <jameskuyper@verizon.net> - 2015-09-06 14:02 -0400
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-09-07 00:31 -0500
                Re: routine for angles needed Keith Thompson <kst-u@mib.org> - 2015-09-06 11:59 -0700
                Re: routine for angles needed Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-06 18:04 -0700
                Re: routine for angles needed Keith Thompson <kst-u@mib.org> - 2015-09-06 18:30 -0700
                Re: routine for angles needed Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-06 18:48 -0700
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-09-07 00:44 -0500
                Re: routine for angles needed Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-10 05:44 -0700
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-08-03 20:16 -0500
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-04 01:26 +0000
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-08-05 02:05 -0500
                Re: routine for angles needed Keith Thompson <kst-u@mib.org> - 2015-08-03 18:33 -0700
                Re: routine for angles needed glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-04 21:24 +0000
                Re: routine for angles needed Robert Wessel <robertwessel2@yahoo.com> - 2015-08-03 19:41 -0500
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:51 -0700
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 12:56 -0700
                Re: routine for angles needed Bartc <bc@freeuk.com> - 2015-08-02 20:57 +0100
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 13:06 -0700
                Re: routine for angles needed Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-02 22:25 +0100
                Re: routine for angles needed Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-02 22:27 +0100
                Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-02 14:40 -0700
  Re: routine for angles needed "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-08-02 19:08 -0700
    Re: routine for angles needed fir <profesor.fir@gmail.com> - 2015-08-03 02:18 -0700
  Re: routine for angles needed danncorbit@gmail.com - 2015-08-12 02:18 -0700
  Re: routine for angles needed bartekltg <bartekltg@gmail.com> - 2015-09-07 05:02 +0200

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