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Project: a good floating point printer/reader.
From: |
Marius Vollmer |
Subject: |
Project: a good floating point printer/reader. |
Date: |
09 May 2002 22:17:13 +0200 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 |
Hi,
I think we need a better floating point printer and or reader. The
current ones can not print denormal numbers, and the string printed
will not always read back as the exact same number (as required by
R5RS).
guile> (define (t x) (= x (string->number (number->string x))))
guile> (t 0.1432987654987436)
#f
guile> (t 0.1432987654987430)
#t
(That is no special number. I just tried a couple until t returned #f.)
guile> (/ 1e-308 2)
#.#
Also, Guile should be able to read denormal number:
guile> 1e-309
ERROR: In procedure string->number:
ERROR: Argument out of range: -309
ABORT: (out-of-range)
Good algorithms might be the ones describes in these two papers:
Printing Floating Point Numbers Quickly and Accurately. Robert
G. Burger and R. Kent Dybvig. ACM SIGPLAN 1996 Conference on
Programming Language Design and Implementation, June
1996.
http://www.cs.indiana.edu/~dyb/FP-Printing-PLDI96.ps.gz
William D Clinger. How to Read Floating Point Numbers Accurately. In
Proceedings of the 1990 ACM Conference on Programming Language
Design and Implementation, pages 92-101.
ftp://ftp.ccs.neu.edu/pub/people/will/howtoread.ps
If anyone wants to work on this, that would be great.
- Project: a good floating point printer/reader.,
Marius Vollmer <=
- Re: Project: a good floating point printer/reader., Rob Browning, 2002/05/13
- Re: Project: a good floating point printer/reader., Marius Vollmer, 2002/05/15
- Re: The Guile license and the use of LGPL libs (like GMP)., Bruce Korb, 2002/05/16
- Re: The Guile license and the use of LGPL libs (like GMP)., Rob Browning, 2002/05/16
- Re: The Guile license and the use of LGPL libs (like GMP)., Carl R. Witty, 2002/05/21
- Re: The Guile license and the use of LGPL libs (like GMP)., Rob Browning, 2002/05/21
- Re: The Guile license and the use of LGPL libs (like GMP)., Jeff Read, 2002/05/16