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Groups > comp.lang.forth > #135386

Re: E.P E. E.EXACT

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.lang.forth
Subject Re: E.P E. E.EXACT
Date 2026-08-22 15:47 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2026Aug22.174706@mips.complang.tuwien.ac.at> (permalink)
References <2026Aug5.200203@mips.complang.tuwien.ac.at> <1156l0r$19nm9$1@dont-email.me> <6a77f77b$1@news.ausics.net> <11592lt$65r8$1@dont-email.me> <nnd$632a7052$6afb2a97@952a43c4d6a59389>

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albert@spenarnc.xs4all.nl writes:
>All floating point numbers are rubbish from a certain point on,

Wrong.

>1E2
> OK
> 100 F.R
> 9.9999999999999999982652765240231929055880755186080932617187500000000000000000000000000000000000000000E1  OK

1E2 can be represented exactly in floating-point, as can all other
integers that fit in the mantissa (i.e., up to 2^53 for binary64 (IEEE
DP FP)).

So in this example either the conversion to FP is "rubbish", to use
your word, or the conversion from FP.  And the problem with the
fallacy that all FP numbers are rubish is that it prevents you from
noticing this.

Here's what you see in Gforth:

1e2 e.exact \ 100e ok

In addition to these integers, there multiples by a power of 2 are
representable until the exponent leaves the normal FP number range.
For subnormal numbers, you get these integers times (for binary64)
2^-1074.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: https://forth-standard.org/
EuroForth 2026 CFP: http://www.euroforth.org/ef26/cfp.html

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Thread

E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-05 18:02 +0000
  Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-06 08:13 -0500
    Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-06 14:00 +0000
      Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-06 10:45 -0500
        Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-06 15:58 +0000
          Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-06 17:20 +0000
        Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-06 21:05 +0200
          Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-06 20:38 +0000
          Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-06 18:44 -0500
          Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-07 11:03 +1000
            Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-07 10:11 +0000
              Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-08 14:39 +1000
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-08 06:32 +0000
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-09 04:50 +1000
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-10 20:01 +1000
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-10 18:06 +0000
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-10 17:24 +0000
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-11 14:01 +1000
                Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-10 22:10 -0500
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-11 04:56 +0000
                Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-11 22:16 -0500
                Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-12 05:47 -0500
                Re: E.P E. E.EXACT peter <peter.noreply@tin.it> - 2026-08-12 18:03 +0200
                Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-12 11:48 -0500
                Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-08 09:14 +0200
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-08 09:40 +0000
                Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-08 15:26 +0200
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-10 16:43 +0000
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-09 13:43 +1000
                Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-09 07:19 +0200
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-10 19:15 +1000
                Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-10 13:17 +0200
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-10 22:59 +1000
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-10 23:54 +1000
                Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-10 20:42 +0200
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-11 17:10 +1000
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-12 14:04 +1000
                Re: E.P E. E.EXACT albert@spenarnc.xs4all.nl - 2026-08-22 16:43 +0200
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-22 15:47 +0000
                Re: E.P E. E.EXACT albert@spenarnc.xs4all.nl - 2026-08-22 18:27 +0200
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-22 16:40 +0000
                Re: E.P E. E.EXACT albert@spenarnc.xs4all.nl - 2026-08-22 19:42 +0200
                Re: E.P E. E.EXACT anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-08-22 18:03 +0000
                Re: E.P E. E.EXACT albert@spenarnc.xs4all.nl - 2026-08-22 22:56 +0200
                Re: E.P E. E.EXACT marcel hendrix <mhx@iae.nl> - 2026-08-23 00:50 +0200
                Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-23 12:25 +1000
                Re: E.P E. E.EXACT Hans Bezemer <the.beez.speaks@gmail.com> - 2026-08-09 14:52 +0200
            Re: E.P E. E.EXACT Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-08-07 07:50 -0500
              Re: E.P E. E.EXACT dxf <dxforth@gmail.com> - 2026-08-08 12:33 +1000
                Re: E.P E. E.EXACT albert@spenarnc.xs4all.nl - 2026-08-22 17:01 +0200
          Re: E.P E. E.EXACT albert@spenarnc.xs4all.nl - 2026-08-22 16:15 +0200

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