Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.arch > #114968

Re: floating pain, Combining Practicality with Perfection

From John Levine <johnl@taugh.com>
Newsgroups comp.arch
Subject Re: floating pain, Combining Practicality with Perfection
Date 2026-02-14 18:12 +0000
Organization Taughannock Networks
Message-ID <10mqdul$dlu$1@gal.iecc.com> (permalink)
References <10llhkk$34374$2@dont-email.me> <1770750645-5857@newsgrouper.org> <10mj1tj$10hdv$1@dont-email.me> <10mq853$106co$1@paganini.bofh.team>

Show all headers | View raw

According to Waldek Hebisch <antispam@fricas.org>:
>quadi <quadibloc@ca.invalid> wrote:
>> 
>> I remember having read one article in a computer magazine where someone 
>> mentioned that an unfortunate result of the transition from the IBM 7090 
>> to the IBM System/360 was that a lot of FORTRAN programs that were able to 
>> use ordinary real nubers had to be switched over to double precision to 
>> yield acceptable results.
>
>Note that IBM floating point format effectively lost about 3 bits of
>accuracy compared to modern 32-bit format.  I am not sure how much they
>lost compared to IBM 7090 but it looks that it was at least 5 bits.
>Assuming that accuracy requirements are uniformly distributed between
>20 and say 60 bits, we can estimate that loss of 5 bits affected about
>25% (or more) of applications that could run using 36-bits.  That is
>"a lot" of programs.
>
>But it does not mean that 36-bits are somewhat magical.  Simply, given
>36-bit machine original author had extra motivation to make sure that
>the program run in 36-bit floating point.

It's worse than that, because the 360's floating point had wobbling precision.
Depending on the number of leading zero bits in the fraction it could lose
anywhere from 1 to 5 bits of precision compared to a rounded binary format.
Hence the badness of the result depended more than usual on the input
data.

IBM had excellent numerical analysts who wrote the widely used Scientific
Subroutine Package which got decent results with 360 arithmetic:

https://bitsavers.org/pdf/ibm/ssp/GH20-0205-4-SSP-programmers_Aug70.pdf

-- 
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

Back to comp.arch | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Combining Practicality with Perfection John Savard <quadibloc@invalid.invalid> - 2026-01-31 18:28 +0000
  Re: Combining Practicality with Perfection jgd@cix.co.uk (John Dallman) - 2026-01-31 22:36 +0000
  Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-05 01:57 +0000
    Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-05 06:06 +0000
      Re: Combining Practicality with Perfection Robert Finch <robfi680@gmail.com> - 2026-02-05 08:10 -0500
      Re: Combining Practicality with Perfection scott@slp53.sl.home (Scott Lurndal) - 2026-02-05 14:50 +0000
      Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-05 23:58 +0000
        Re: Combining Practicality with Perfection jgd@cix.co.uk (John Dallman) - 2026-02-06 16:37 +0000
          Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-06 22:32 +0000
            Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-06 22:34 +0000
            Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-07 00:57 +0000
              Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-07 02:45 +0000
          Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-06 22:40 +0000
        Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-09 22:46 +0000
          Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-10 03:49 +0000
            Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-10 19:10 +0000
              Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-11 23:04 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-11 23:55 +0000
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-12 06:04 +0000
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-24 00:22 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-24 19:32 +0000
                Re: Combining Practicality with Perfection jgd@cix.co.uk (John Dallman) - 2026-10-25 06:00 +0000
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-25 17:38 +0000
                Re: Combining Practicality with Perfection Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-10-25 22:43 -0700
                Re: Combining Practicality with Perfection jgd@cix.co.uk (John Dallman) - 2026-10-26 09:35 +0000
                Re: Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-10-26 19:53 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-26 13:40 +0000
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-26 22:05 +0000
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-26 22:12 +0000
                Re: Combining Practicality with Perfection Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-10-26 20:13 -0700
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-27 14:30 +0000
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-26 22:09 +0000
                Re: Combining Practicality with Perfection EricP <ThatWouldBeTelling@thevillage.com> - 2026-10-26 18:20 -0400
                Re: Combining Practicality with Perfection quadibloc@invalid.com (John Savard) - 2026-10-27 03:00 +0000
                Re: Combining Practicality with Perfection antispam@fricas.org (Waldek Hebisch) - 2026-10-26 22:51 +0000
                Re: Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-10-25 18:47 +0000
                Re: Combining Practicality with Perfection David Schultz <david.schultz@earthlink.net> - 2026-02-11 17:57 -0600
                Re: Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-02-12 00:04 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-12 02:04 +0000
                Re: Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-02-12 03:31 +0000
                Hex floating point (was: Combining Practicality with Perfection) Thomas Koenig <tkoenig@netcologne.de> - 2026-02-15 16:53 +0000
                Re: Combining Practicality with Perfection anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-02-12 08:45 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-12 17:09 +0000
                Re: Combining Practicality with Perfection Terje Mathisen <terje.mathisen@tmsw.no> - 2026-02-14 18:03 +0100
                Re: Combining Practicality with Perfection BGB <cr88192@gmail.com> - 2026-02-19 02:10 -0600
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-19 17:30 +0000
                Re: Combining Practicality with Perfection Michael S <already5chosen@yahoo.com> - 2026-02-19 20:15 +0200
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-19 19:55 +0000
                Re: Combining Practicality with Perfection BGB <cr88192@gmail.com> - 2026-02-20 05:08 -0600
                Re: Combining Practicality with Perfection Terje Mathisen <terje.mathisen@tmsw.no> - 2026-02-20 15:22 +0100
                Re: Combining Practicality with Perfection BGB <cr88192@gmail.com> - 2026-02-20 15:26 -0600
                Re: Combining Practicality with Perfection Paul Clayton <paaronclayton@gmail.com> - 2026-02-21 20:27 -0500
                Re: Combining Practicality with Perfection Michael S <already5chosen@yahoo.com> - 2026-02-12 10:49 +0200
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-12 17:10 +0000
                Re: Combining Practicality with Perfection Michael S <already5chosen@yahoo.com> - 2026-02-12 23:38 +0200
                Re: Combining Practicality with Perfection Terje Mathisen <terje.mathisen@tmsw.no> - 2026-02-12 14:28 +0100
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-12 05:51 +0000
                Re: Combining Practicality with Perfection Michael S <already5chosen@yahoo.com> - 2026-02-12 10:53 +0200
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-12 18:40 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-12 20:02 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-12 20:33 +0000
                Re: Combining Practicality with Perfection Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-02-11 19:50 -0800
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-12 05:55 +0000
                Re: Combining Practicality with Perfection Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-02-12 08:40 -0800
                Re: Combining Practicality with Perfection scott@slp53.sl.home (Scott Lurndal) - 2026-02-12 16:51 +0000
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-12 18:49 +0000
                Re: Combining Practicality with Perfection scott@slp53.sl.home (Scott Lurndal) - 2026-02-12 15:54 +0000
                Re: Combining Practicality with Perfection Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-02-12 08:52 -0800
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-12 18:37 +0000
                Re: Combining Practicality with Perfection antispam@fricas.org (Waldek Hebisch) - 2026-02-14 16:33 +0000
                Re: floating pain, Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-02-14 18:12 +0000
                Re: floating pain, Combining Practicality with Perfection antispam@fricas.org (Waldek Hebisch) - 2026-02-17 01:16 +0000
                Re: floating pain, Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-02-17 01:24 +0000
                Re: floating pain, Combining Practicality with Perfection antispam@fricas.org (Waldek Hebisch) - 2026-02-17 16:21 +0000
                Re: floating pain, Combining Practicality with Perfection John Levine <johnl@taugh.com> - 2026-02-17 19:20 +0000
                Re: floating pain, Combining Practicality with Perfection antispam@fricas.org (Waldek Hebisch) - 2026-02-17 19:52 +0000
                Re: floating pain, Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-17 19:09 +0000
                Re: Combining Practicality with Perfection jgd@cix.co.uk (John Dallman) - 2026-02-15 14:37 +0000
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-17 18:57 +0000
                Re: Combining Practicality with Perfection antispam@fricas.org (Waldek Hebisch) - 2026-02-17 20:43 +0000
                Re: Combining Practicality with Perfection MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-02-18 00:50 +0000
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-18 08:52 +0000
                Re: Combining Practicality with Perfection Robert Finch <robfi680@gmail.com> - 2026-02-18 08:40 -0500
                Re: Combining Practicality with Perfection quadi <quadibloc@ca.invalid> - 2026-02-20 08:14 +0000
                Re: Combining Practicality with Perfection Thomas Koenig <tkoenig@netcologne.de> - 2026-02-19 18:49 +0000

csiph-web