Re: Q: division vs multiplication

leichter@zodiac.rutgers.edu
Tue, 11 Apr 1995 16:52:28 GMT

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Related articles
[5 earlier articles]
Re: Q: division vs multiplication davidm@Rational.COM (1995-04-03)
Re: Q: division vs multiplication brandis@inf.ethz.ch (1995-04-04)
Re: Q: division vs multiplication Terje.Mathisen@hda.hydro.com (1995-04-06)
Re: Q: division vs multiplication meissner@cygnus.com (Mike Meissner) (1995-04-16)
Re: Q: division vs multiplication martens@cis.ohio-state.edu (1995-04-16)
Re: Q: division vs multiplication jmccarty@spdmail.spd.dsccc.com (1995-04-18)
Re: Q: division vs multiplication leichter@zodiac.rutgers.edu (1995-04-11)
Re: Q: division vs multiplication kptben@aol.com (1995-04-17)
Re: Q: division vs multiplication pcg@aber.ac.uk (1995-04-17)
Re: Q: division vs multiplication gsc@magna.com.au (1995-04-18)
Re: Q: division vs multiplication jbuck@Synopsys.COM (1995-04-28)
Re: Q: division vs multiplication davidm@flora.Rational.com (1995-04-28)
Re: Q: division vs multiplication Roger@natron.demon.co.uk (Roger Barnett) (1995-04-28)
[1 later articles]
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Newsgroups: comp.compilers
From: leichter@zodiac.rutgers.edu
Keywords: arithmetic
Organization: Rutgers University Department of Computer Science
References: 95-04-003 95-04-059
Date: Tue, 11 Apr 1995 16:52:28 GMT

  davidm@Rational.COM (David Moore) writes:
| [ASIDE]. A year or two ago, there were a couple of papers that
| appeared together somewhere, and which I know I have, but which I
| have been unable to locate. One was entitled something like "How to
| write floating point numbers" and the other "How to read floating
| point numbers".
|
| Can anyone give me the reference?


A bit more than a year or two ago - time does fly, doesn't it? See:
Proceedings of the SIGPLAN'90 Conference on Programming Language Design and
Implementation; appeared as SIGPLAN Notices 25(6). The paper on printing
floating-point numbers is by Steele and White; the one on reading them by
Clinger. The actual titles are: "How to [read|print] floating-point numbers
accurately".


I've always wondered whether the authors planned to submit their papers
together, or whether they coincidentally submitted to the same conference
and adjusted the titles later.


A related algorithm, due I believe to Lyle Ramshaw: Given a floating-point
specification equivalent to C's %f with no explicit precision, how much digits
of precision should you actually use? Ramshaw's answer is the only thought-
through one that I've seen: "%f" prints the decimal representation R of a
floating point value F with two properties: If R is read back by the corres-
ponding input conversion on a machine with the same internal representation,
it gets back exactly F; and no decimal representation R' that also, when read,
produces F, is shorter than R. I'm sure the algorithm - which is efficient
enough to be used in the standard Modula-3 libraries - has been published, but
I don't have a reference. (A reference almost certainly appears in the
Modula-3 library documentation.)
-- Jerry
--


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