Re: Updating C default type

From	glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups	comp.lang.c
Subject	Re: Updating C default type
Date	2014-05-26 05:48 +0000
Organization	Aioe.org NNTP Server
Message-ID	<llukj0$ctf$1@speranza.aioe.org> (permalink)
References	<lj66ho$8fg$1@speranza.aioe.org> <lj6bsg$nji$1@speranza.aioe.org> <u1jsm9pis06srf0rathl2jm22mmhcjq9jn@4ax.com>

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David Thompson <dave.thompson2@verizon.net> wrote:

(snip, I wrote)

>> Also, note that floating point and integer aren't the only possible
>> data types. There are systems that allow for non-integer fixed
>> point values that have a fixed number of (decimal or binary or ...)
>> digits after the radix point. Note that in most countries money
>> is commonly described in a system with two digits after the decimal
>> point. PL/I even allows for a negative number of digits after
>> the radix (two or ten) point. 

> AFAIK all applicable machines actually implement integers in largish
> or varying length binary, or decimal, or (usually) both. When you
> declare things like PL/I FIXED DEC(8,4) or COBOL PIC 9999.9999 or Ada
> delta .0001 the compiler and/or the language runtime library handles
> scaling integers to get fixed-point. IIRC PL/I in particular had
> rather unusual rules for fixed-point division which were entirely its
> own and not from the underlying machine. (COBOL can do 'negative'
> fractional digits, but only decimal at least standardly.)

The IBM description of fixed point instruction in the Principles
of Operations manuals for S/360 and successors describes then in
terms of fixed point where the user is expected to keep track of
the radix point, and not as integers. (Similar to the way
slide rule users are expected to keep track of the decimal
point.) The OS/360 assembler knows how to scale values, given 
a scale factor. (At least for binary constants, I am not so 
sure about decimal constants.) 

PL/I allows a pretty wide range, both positive and negative,
for the scale factor, and it applies to both decimal and binary
bases. 

While most IBM S/360 and successor PL/I compilers used BCD
arithmetic for FIXED BIN, some (CALL/OS for one) used binary.

-- glen

Thread

Updating C default type Raj Pashwar <raj121190@hotmail.NOSPAM.com> - 2014-04-22 16:48 +0000
  Re: Updating C default type jacob navia <jacob@spamsink.net> - 2014-04-22 18:59 +0200
    Re: Updating C default type Raj Pashwar <raj121190@hotmail.NOSPAM.com> - 2014-04-22 17:13 +0000
      Re: Updating C default type Keith Thompson <kst-u@mib.org> - 2014-04-22 11:59 -0700
      Re: Updating C default type Kaz Kylheku <kaz@kylheku.com> - 2014-04-22 19:12 +0000
        Re: Updating C default type jacob navia <jacob@spamsink.net> - 2014-04-25 19:31 +0200
      Re: Updating C default type Stephen Sprunk <stephen@sprunk.org> - 2014-04-22 15:41 -0500
      Re: Updating C default type "BartC" <bc@freeuk.com> - 2014-04-22 21:47 +0100
      Re: Updating C default type Ken Brody <kenbrody@spamcop.net> - 2014-04-24 12:25 -0400
        Re: Updating C default type Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-24 10:32 -0700
        Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-24 20:17 +0000
        Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-24 21:03 +0000
    Re: Updating C default type Gareth Owen <gwowen@gmail.com> - 2014-04-22 19:12 +0100
  Re: Updating C default type Keith Thompson <kst-u@mib.org> - 2014-04-22 10:26 -0700
  Re: Updating C default type Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-22 10:28 -0700
  Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-22 18:20 +0000
    Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-22 19:09 +0000
      Re: Updating C default type James Kuyper <jameskuyper@verizon.net> - 2014-04-22 15:35 -0400
        Re: Updating C default type James Kuyper <jameskuyper@verizon.net> - 2014-04-22 15:38 -0400
        Re: Updating C default type Kaz Kylheku <kaz@kylheku.com> - 2014-04-22 19:54 +0000
          Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-22 21:27 +0000
            Re: Updating C default type "BartC" <bc@freeuk.com> - 2014-04-22 23:08 +0100
    Re: Updating C default type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-04-22 22:03 +0100
    Re: Updating C default type Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-04-23 09:59 +0200
    Re: Updating C default type David Thompson <dave.thompson2@verizon.net> - 2014-05-25 16:44 -0400
      Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-05-26 05:48 +0000
  Re: Updating C default type "Osmium" <r124c4u102@comcast.net> - 2014-04-22 14:01 -0500
    Re: Updating C default type Quentin Pope <qp19433@hotmail.NOSPAM.com> - 2014-04-23 16:57 +0000
      Re: Updating C default type James Kuyper <jameskuyper@verizon.net> - 2014-04-23 13:13 -0400
      Re: Updating C default type Kaz Kylheku <kaz@kylheku.com> - 2014-04-23 18:02 +0000
      Re: Updating C default type Keith Thompson <kst-u@mib.org> - 2014-04-23 11:33 -0700
  Re: Updating C default type Kaz Kylheku <kaz@kylheku.com> - 2014-04-22 19:08 +0000
    Re: Updating C default type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-04-22 22:08 +0100
      Re: Updating C default type "BartC" <bc@freeuk.com> - 2014-04-22 22:19 +0100
    Re: Updating C default type Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-22 14:13 -0700
      Re: Updating C default type Stephen Sprunk <stephen@sprunk.org> - 2014-04-23 11:55 -0500
        Re: Updating C default type Keith Thompson <kst-u@mib.org> - 2014-04-23 10:55 -0700
          Re: Updating C default type Robert Wessel <robertwessel2@yahoo.com> - 2014-04-24 00:03 -0500
        Re: Updating C default type Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-23 22:37 -0700
          Re: Updating C default type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-24 12:05 +0000
      Re: Updating C default type gordonb.ez7sl@burditt.org (Gordon Burditt) - 2014-04-25 06:11 -0500
        Re: Updating C default type James Kuyper <jameskuyper@verizon.net> - 2014-04-25 08:48 -0400
  Re: Updating C default type Stephen Sprunk <stephen@sprunk.org> - 2014-04-22 15:30 -0500
    Re: Updating C default type ralph <nt_consulting@yahoo.com> - 2014-04-22 23:18 -0500
  Re: Updating C default type Ken Brody <kenbrody@spamcop.net> - 2014-04-24 12:28 -0400
  Re: Updating C default type gordonb.oztxz@burditt.org (Gordon Burditt) - 2014-04-24 23:50 -0500
    Re: Updating C default type James Kuyper <jameskuyper@verizon.net> - 2014-04-25 08:41 -0400
  Re: Updating C default type Hans Vlems <hvlems@freenet.de> - 2014-05-25 23:57 -0700
    Re: Updating C default type Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-05-26 01:55 -0700
    Re: Updating C default type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-05-26 13:01 +0100
      Re: Updating C default type Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-05-26 13:12 -0700
        Re: Updating C default type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-05-26 22:31 +0100
          Re: Updating C default type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-05-26 23:55 +0100
          Re: Updating C default type Keith Thompson <kst-u@mib.org> - 2014-05-26 17:11 -0700
    Re: Updating C default type James Kuyper <jameskuyper@verizon.net> - 2014-05-27 07:54 -0400

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