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Groups > comp.lang.forth > #43636
| From | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
|---|---|
| Newsgroups | comp.lang.forth |
| Subject | Re: RfD: D>F and S>F first draft |
| Date | 2015-11-22 14:29 +0000 |
| Organization | Institut fuer Computersprachen, Technische Universitaet Wien |
| Message-ID | <2015Nov22.152931@mips.complang.tuwien.ac.at> (permalink) |
| References | <n2qss7$2mo$1@dont-email.me> |
C G Montgomery <cgm@physics.utoledo.edu> writes:
>Proposal:
>
>In 2.6.1.1130 D>F (d -- )(F: -- r) replace
>"r is the floating point equivalent of d. An ambiguous condition exists
>if d can not be precisely represented as a floating-point value"
>with
>"r is the floating-point value which is nearest to d in the sense of
>'round to nearest' as given in 12.3.2."
>
>In 12.6.2.2175 S>F (n -- )(F: -- r) replace
>"r is the floating-point equivalent of the single-cell value n. An
>ambiguous condition exists if n can not be precisely represented as a
>floating-point value."
>with
>"r is the floating-point value which is nearest to n in the sense of
>'round to nearest' as given in 12.3.2."
Looks good to me.
>Implementation and Testing:
>
>For any system which provides the FLOATING and FLOATING EXT word sets and
>does not already comply with this proposal it should not be difficult to
>implement.
>Whether floating-point support is in hardware or software, if FROUND can
>be provided
>it should be no harder to provide the proposed behavior of D>F and S>F.
Actually FROUND is relatively easy to provide if you have
round-to-nearest/even addition:
#define X (1024.*1024.*1024.*1024.*1024.*8.)
if (r<0.0)
return (r+X)-X;
else
return (r-X)+X;
The X here is defined for IEEE doubles. But that does not help
implementing the rounding for D>F and S>F. Still, e.g., Intel CPUs
provide various instructions for converting that round to nearest.
One problem is to avoid double rounding if you have to deal with more
integer bits than these instructions handle: If the conversion for the
most significant part already rounds in the wrong direction, adding
the conversion of the least significant part afterwards will not
correct that. The current Gforth code contains an implementation
variant that has this problem.
>The intentional flexibility of the Standard in specifying floating point
>internal representations makes it difficult to provide tests which have
>universal applicability to all Standard systems.
Well, testing that
1 MAX-N D>F
gives the same result as
0 MAX-N D>F 1e f+
should be better than nothing.
- 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: http://www.forth200x.org/forth200x.html
EuroForth 2015: http://www.rigwit.co.uk/EuroForth2015/
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RfD: D>F and S>F first draft C G Montgomery <cgm@physics.utoledo.edu> - 2015-11-21 17:59 -0500
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-22 18:25 +1100
Re: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-11-22 06:20 -0800
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-23 10:58 +1100
Re: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-23 02:57 +0100
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-24 13:16 +1100
Re: D>F and S>F first draft Paul Rubin <no.email@nospam.invalid> - 2015-11-23 18:49 -0800
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-25 11:51 +1100
Re: D>F and S>F first draft Paul Rubin <no.email@nospam.invalid> - 2015-11-24 17:26 -0800
Re: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-25 02:43 +0100
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-26 12:16 +1100
Re: D>F and S>F first draft Paul Rubin <no.email@nospam.invalid> - 2015-11-25 17:47 -0800
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-26 15:47 +1100
Re: D>F and S>F first draft Paul Rubin <no.email@nospam.invalid> - 2015-11-25 23:07 -0800
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-26 07:27 +0000
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-26 09:19 +0000
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-28 04:26 +1100
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-28 11:31 +0000
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-29 20:23 +1100
Re: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-29 20:39 +0100
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-12-05 17:48 +1100
Re: D>F and S>F first draft Julian Fondren <julian.fondren@gmail.com> - 2015-12-04 23:58 -0800
Re: D>F and S>F first draft mhx@iae.nl - 2015-12-05 02:19 -0800
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-12-05 11:25 +0000
Re: D>F and S>F first draft Albert van der Horst <albert@spenarnc.xs4all.nl> - 2015-12-05 13:11 +0000
Re: D>F and S>F first draft mhx@iae.nl - 2015-12-05 05:27 -0800
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-12-05 15:33 +0000
Re: D>F and S>F first draft mhx@iae.nl - 2015-12-07 10:10 -0800
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-12-09 16:58 +0000
Re: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-12-06 10:23 -0800
Re: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-12-06 21:37 +0100
Re: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-12-05 19:08 +0100
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-30 08:33 +0000
Re: D>F and S>F first draft "Elizabeth D. Rather" <erather@forth.com> - 2015-11-25 21:43 -1000
Re: D>F and S>F first draft "HAA" <someone@microsoft.com> - 2015-11-28 19:28 +1100
Re: D>F and S>F first draft Albert van der Horst <albert@spenarnc.xs4all.nl> - 2015-11-26 11:37 +0000
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-22 15:10 +0000
Re: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-22 20:48 +0100
Re: D>F and S>F first draft "Elizabeth D. Rather" <erather@forth.com> - 2015-11-22 13:42 -1000
Re: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-23 11:50 +0000
Re: D>F and S>F first draft "Elizabeth D. Rather" <erather@forth.com> - 2015-11-23 12:46 -1000
Forth libraries Lars Brinkhoff <lars.spam@nocrew.org> - 2015-11-24 08:55 +0100
Re: RfD: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-11-22 06:33 -0800
Re: RfD: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-22 16:00 +0000
Re: RfD: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-11-22 08:53 -0800
Re: RfD: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-11-22 09:11 -0800
Re: RfD: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-22 18:24 +0000
Re: RfD: D>F and S>F first draft Paul Rubin <no.email@nospam.invalid> - 2015-11-22 09:07 -0800
Re: RfD: D>F and S>F first draft stephen@mpeforth.com (Stephen Pelc) - 2015-11-22 18:10 +0000
Re: RfD: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-22 18:26 +0000
Re: RfD: D>F and S>F first draft rickman <gnuarm@gmail.com> - 2015-11-22 13:58 -0500
Re: RfD: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-23 12:34 +0000
Re: RfD: D>F and S>F first draft Albert van der Horst <albert@spenarnc.xs4all.nl> - 2015-11-23 16:39 +0000
Re: RfD: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-24 03:00 +0100
Re: RfD: D>F and S>F first draft Lars Brinkhoff <lars.spam@nocrew.org> - 2015-11-23 13:48 +0100
Re: RfD: D>F and S>F first draft mhx@iae.nl - 2015-11-23 05:19 -0800
Re: RfD: D>F and S>F first draft mhx@iae.nl - 2015-11-23 16:09 -0800
Re: RfD: D>F and S>F first draft Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-22 20:42 +0100
Re: RfD: D>F and S>F first draft C G Montgomery <cgm@physics.utoledo.edu> - 2015-11-22 16:43 -0500
Re: RfD: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-11-22 18:40 -0800
Re: RfD: D>F and S>F first draft krishna.myneni@ccreweb.org - 2015-11-22 18:51 -0800
Re: RfD: D>F and S>F first draft C G Montgomery <cgm@physics.utoledo.edu> - 2015-11-25 15:47 -0500
Re: RfD: D>F and S>F first draft anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-22 14:29 +0000
Re: RfD: D>F and S>F first draft "David N. Williams" <williams@umich.edu> - 2015-11-22 10:41 -0600
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