From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: Array of Variant Records Question...
Date: 1999/09/23
Date: 1999-09-23T00:00:00+00:00 [thread overview]
Message-ID: <7sdcih$6s9$1@nnrp1.deja.com> (raw)
In-Reply-To: 37E922DE.9007776F@mitre.org
In article <37E922DE.9007776F@mitre.org>,
"Robert I. Eachus" <eachus@mitre.org> wrote:
> Robert A Duff wrote:
>
> > I don't know much about the theory of these things, but I
was under the
> > impression that Random can never ever return the same value
twice in a
> > row. Robert Eachus or somebody can tell us for sure.
>
> See previous post. There is a major distiction here
between a
> floating-point generator and an integer or fixed-point
generator. In an
> idealized enivronment, a floating-point generator would have
zero chance
> of
> returning the same value twice in a row.
You mean "real" instead of "floating-point", please do not use
floating-point to mean the real numbers of mathematics, they
are quite different. The term floating-point should be reserved
to computer number systems, which are not in any sense
non-ideal. They have well defined semantics which just happen
to be different from those of real arithmetic.
Since we never have real arithmetic on computers, talking about
this case is a red herring that has nothing to do with anything
we are interested in here.
> But in a computer environment where
> floating point values are represented by a finite set of
values, there
> should be a small but finite probability that two succesive
values are
> the same.
Yes, and that is what is important, and to say it again, there
is nothing "non-ideal" about this situation. Thinking of
computer floating-point as a non-ideal approximation of
real arithmetic is helpful only at a very simple level of
abstraction, and is not useful for serious numeric work.
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next prev parent reply other threads:[~1999-09-23 0:00 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-09-08 0:00 Array of Variant Records Question Bruce Detter
1999-09-08 0:00 ` Ted Dennison
1999-09-08 0:00 ` Matthew Heaney
1999-09-08 0:00 ` Mike Silva
1999-09-08 0:00 ` Matthew Heaney
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Matthew Heaney
1999-09-09 0:00 ` Matthew Heaney
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Mark Lundquist
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Brian Rogoff
1999-09-13 0:00 ` Matthew Heaney
1999-09-13 0:00 ` Robert A Duff
1999-09-13 0:00 ` Matthew Heaney
1999-09-13 0:00 ` Brian Rogoff
1999-09-14 0:00 ` Robert Dewar
1999-09-14 0:00 ` Robert Dewar
1999-09-14 0:00 ` Brian Rogoff
1999-09-09 0:00 ` Matthew Heaney
1999-09-10 0:00 ` Robert Dewar
1999-09-10 0:00 ` Mark Lundquist
1999-09-10 0:00 ` Matthew Heaney
1999-09-11 0:00 ` Jean-Pierre Rosen
1999-09-14 0:00 ` "cast away const" (was Re: Array of Variant Records Question...) Mark Lundquist
[not found] ` <wccd7viiv59.fsf@world.std.com>
[not found] ` <7rrmqd$l89@drn.newsguy.com>
[not found] ` <wcciu59n2uf.fsf@world.std.com>
1999-09-22 0:00 ` Array of Variant Records Question Robert I. Eachus
1999-09-23 0:00 ` Robert Dewar [this message]
1999-09-23 0:00 ` Robert I. Eachus
1999-09-22 0:00 ` Robert I. Eachus
1999-09-10 0:00 ` Mark Lundquist
1999-09-10 0:00 ` Matthew Heaney
1999-09-11 0:00 ` Robert Dewar
1999-09-11 0:00 ` Richard D Riehle
1999-09-13 0:00 ` Hyman Rosen
1999-09-14 0:00 ` Mark Lundquist
[not found] ` <7roohh$s6r@dfw-ixnews7.ix.netcom.com>
[not found] ` <37e01168@news1.prserv.net>
[not found] ` <7rp86o$c6h@dfw-ixnews3.ix.netcom.com>
[not found] ` <37E18CC6.C8D431B@rational.com>
[not found] ` <7rs8bn$s6@dfw-ixnews4.ix.netcom.com>
[not found] ` <wccemfxn15s.fsf@world.std.com>
1999-09-22 0:00 ` 'constant functions' and access constant params (was Re: Array of Variant Records Question...) Richard D Riehle
[not found] ` <37e2e58c@news1.prserv.net>
1999-09-22 0:00 ` Richard D Riehle
1999-09-22 0:00 ` Mark Lundquist
1999-09-22 0:00 ` Mark Lundquist
1999-09-22 0:00 ` Matthew Heaney
1999-09-22 0:00 ` Richard D Riehle
1999-09-22 0:00 ` Matthew Heaney
1999-09-22 0:00 ` Matthew Heaney
1999-09-23 0:00 ` Vincent Marciante
1999-09-23 0:00 ` Matthew Heaney
1999-09-24 0:00 ` Robert A Duff
1999-09-25 0:00 ` Matthew Heaney
1999-09-27 0:00 ` Richard D Riehle
1999-09-27 0:00 ` Richard D Riehle
1999-09-27 0:00 ` David Kristola
1999-09-23 0:00 ` Robert Dewar
1999-09-27 0:00 ` Richard D Riehle
1999-09-28 0:00 ` Robert Dewar
1999-09-28 0:00 ` "Competence" (was: 'constant functions' and access constant params) Ted Dennison
1999-09-28 0:00 ` Robert Dewar
1999-09-28 0:00 ` 'constant functions' and access constant params (was Re: Array of Variant Records Question...) Robert Dewar
1999-09-28 0:00 ` Richard D Riehle
1999-09-29 0:00 ` Robert Dewar
1999-09-29 0:00 ` Robert A Duff
1999-09-10 0:00 ` Proposed Ada features " Mark Lundquist
1999-09-10 0:00 ` Matthew Heaney
1999-09-10 0:00 ` tmoran
1999-09-09 0:00 ` Array of Variant Records Question Nick Roberts
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Tucker Taft
1999-09-10 0:00 ` Nick Roberts
1999-09-08 0:00 ` Thank you Bruce Detter
1999-09-08 0:00 ` Martin C. Carlisle
1999-09-08 0:00 ` Array of Variant Records Question Martin C. Carlisle
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