Re: R-alpha: .Machine object

Friedrich Leisch (Friedrich.Leisch@ci.tuwien.ac.at)
Wed, 13 Nov 1996 09:15:07 +0100


Date: Wed, 13 Nov 1996 09:15:07 +0100
Message-Id: <199611130815.JAA31488@galadriel.ci.tuwien.ac.at>
From: Friedrich Leisch <Friedrich.Leisch@ci.tuwien.ac.at>
To: Ross Ihaka <ihaka@stat.auckland.ac.nz>
Subject: Re: R-alpha: .Machine object
In-Reply-To: <199611122206.LAA26686@stat13.stat.auckland.ac.nz>
 <199611122206.LAA26686@stat13.stat.auckland.ac.nz>

>>>>> On Wed, 13 Nov 1996 11:06:11 +1300 (NZDT),
>>>>> Ross Ihaka wrote:

> Friedrich Leisch writes:
>> 
>> Hi,
>> 
>> I would like to port the S fracdiff package to R. Everything works
>> fine, except that I need the S .Machine object, providing a lot of
>> Machine constants such as max double, min double, eps, aso
>> 
>> Are there any plans on including .Machine in one of the next releases?

> The S .Machine object seems to include all sorts of information I
> can't really see a use for (isn't virtually everything ieee these days?).

> I have some code which will certainly produce all this information,
> but it would be cleaner just to use the useful subset of values in
> <float.h> and <limits.h>.  We could give them the same names as the S
> values.

> Also, since R is strictly double precision it seems to make sense only
> to have the double precision versions of these values.

> Opinions anyone?


obviously we don't need the single values.

I did a grep on .Machine in the statlib S directory and found only the
following .Machine values:

	.Machine$double.eps
	.Machine$double.neg.eps
	.Machine$double.xmax
	.Machine$double.xmin
	.Machine$single.eps
	.Machine$single.xmax

where only

	.Machine$double.eps
	.Machine$double.neg.eps
	.Machine$double.xmax
	.Machine$double.xmin

are relevant to us. this also happen to be exactly the values I needed
in first place :-)

from this it seems obvious that we need only a small subset (probably
not as small as the above)

additionally, e.g.,  integer.max seems important to me.

Greetings,
Fritz

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                          Friedrich  Leisch 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Institut für Statistik                        Tel: (+43 1) 58801 4541
 Technische Universität Wien                   Fax: (+43 1)  504 14 98
 Wiedner Hauptstraße 8-10/1071        Friedrich.Leisch@ci.tuwien.ac.at
 A-1040 Wien, Austria               http://www.ci.tuwien.ac.at/~leisch
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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