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| From | mhx@iae.nl (Marcel Hendrix) |
|---|---|
| Subject | Re: CfV: S>F and F>S |
| Newsgroups | comp.lang.forth |
| Message-ID | <19171400958435@frunobulax.edu> (permalink) |
| Date | 2012-08-03 21:18 +0200 |
| References | <2857190.v9o6eJ1jg5@sunwukong.fritz.box> |
| Organization | Wanadoo |
Bernd Paysan <bernd.paysan@gmx.de> writes Re: CfV: S>F and F>S
[..]
> I don't think we have to remove it. We simply have to state that if the
> floating point number doesn't fit into an integer, this is an ambiguous
> condition. We could specify F>S to have the same rounding mode as F>D,
> but then, yes, we have the problem that F>D does not specify a rounding
> mode (which is not really nice to easily write portable programs).
I am probably going to end up with egg on my face.
F>D "f-to-d" FLOAT
( -- d ) ( F: r -- )
d is the double-cell signed integer equivalent to the integer portion of
r. The fractional portion of r is discarded. An ambiguous condition
exists if the integer portion of r cannot be precisely represented as a
double-cell signed integer.
*The fractional portion of r is discarded*
Why do I need to know the rounding mode for this?
1.0001e F>S . 1
0.5e F>S . 0
0.999e F>S . 0
-0.999e F>S . 0
-1e F>S . -1
Yes, I must do something to the 'rounding mode' to get this *integer
portion*, but the Forth code does not need to know what that is to
recognize I have provided the correct result.
Note also that the spec. says "SIGNED integer equivalent." Doing
F>D DROP is certainly not preserving the sign, so I'd argue it is
against the spirit of F>D .
-marcel
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CfV: S>F and F>S anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-02 16:51 +0000
Re: CfV: S>F and F>S mhx@iae.nl (Marcel Hendrix) - 2012-08-02 22:28 +0200
Re: CfV: S>F and F>S Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-02 23:36 +0200
Re: CfV: S>F and F>S Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-08-03 04:39 -0700
Re: CfV: S>F and F>S Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-03 19:56 +0200
Re: CfV: S>F and F>S mhx@iae.nl (Marcel Hendrix) - 2012-08-03 21:18 +0200
Re: CfV: S>F and F>S anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-04 09:50 +0000
Re: CfV: S>F and F>S Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-04 21:51 +0200
Presence of standard words (was: CfV: S>F and F>S) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-05 11:07 +0000
Re: Presence of standard words (was: CfV: S>F and F>S) stephenXXX@mpeforth.com (Stephen Pelc) - 2012-08-05 11:34 +0000
Re: Presence of standard words (was: CfV: S>F and F>S) Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-05 13:59 +0200
Re: Presence of standard words (was: CfV: S>F and F>S) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-06 11:22 +0000
Re: CfV: S>F and F>S Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-08-04 04:50 -0700
Re: CfV: S>F and F>S stephenXXX@mpeforth.com (Stephen Pelc) - 2012-08-04 12:30 +0000
Re: CfV: S>F and F>S C G Montgomery <cgm@physics.utoledo.edu> - 2012-08-05 09:14 -0400
Re: CfV: S>F and F>S Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-04 21:47 +0200
Re: CfV: S>F and F>S Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-08-04 05:42 -0700
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