0004948: There are many NaNs

View Issue Details [ Jump to Notes ]

[ Issue History ] [ Print ]

Project

Category

View Status

Date Submitted

Last Update

0004948

OCaml

OCaml documentation

public

2009-12-23 03:33

2012-04-10 17:58

Reporter

dbuenzli

Assigned To

Priority

normal

Severity

tweak

Reproducibility

N/A

Status

resolved

Resolution

won't fix

Platform

OS Version

Product Version

3.11.1

Target Version

Fixed in Version

Summary

0004948: There are many NaNs

Description

The documentation makes it sound like there exists a single NaN value.

The following improvements could be done :

1) In the documentation of compare, note that compare equates all NaN value.
2) In the paragraph preceding floating point functions, indicate that
   0. /. 0. returns a NaN value (instead of Pervasives.nan) and that
   any function taking a NaN (instead of Pervasives.nan) value returns a
   NaN value (instead of Pervasives.nan).
3) In the documentation of Pervasives.nan, indicate that nan is a NaN value
   but that may not be the one you get in 0. /. 0.

Tags

No tags attached.

Attached Files

Relationships

related to

0005038

closed

xleroy

Int64.float_of_bits weirdness on x86 ports

Notes
(0005212) xleroy (administrator) 2009-12-30 16:00	Yes, IEEE 754 allows for multiple NaN values, and I've never seen a program take advantage of that. But the point is that all these NaNs are not distinguishable from Caml: as you noticed, they compare equal according to Pervasives.compare. So, I don't see the need to complicate the documentation to talk about something that is invisible to the programmer.

(0005215) dbuenzli (reporter) 2009-12-30 17:42	Maybe you are right, it's not worth it for the casual user. In fact I was just surprised by this : # compare nan (0. /. 0.);; - : int = 0 # compare (Int64.bits_of_float nan) (Int64.bits_of_float (0. /. 0.));; - : int = 1

(0007314) doligez (manager) 2012-04-10 17:58	I think we agree we don't want to trouble normal users with the minute details of NaN specifications. I'm closing this PR.

Issue History
Date Modified	Username	Field	Change
2009-12-23 03:33	dbuenzli	New Issue
2009-12-30 16:00	xleroy	Note Added: 0005212
2009-12-30 16:00	xleroy	Status	new => feedback
2009-12-30 17:42	dbuenzli	Note Added: 0005215
2010-04-29 19:28	xleroy	Relationship added	related to 0005038
2012-04-10 17:58	doligez	Note Added: 0007314
2012-04-10 17:58	doligez	Status	feedback => resolved
2012-04-10 17:58	doligez	Resolution	open => won't fix