To: J3 J3/02-156
From: Subgroup C
Date: 27 February 2002
Subject: Unresolved issue #344, rounding modes, 10.6.1.2.6
Unresolved issue #344 p. 219 raises two issues:
1. Round to zero mode is not precisely specified.
2. Are the specifications identical to the IEEE requirements
for UP and DOWN?
The following edits resolve these issues.
Edits:
#1 of issue 344:
( Rephrase the IEEE words in Fortran-speak. The IEEE words
are: "the result shall be the format's value closest to and
no greater in magnitude than the infinitely precise result".
I don't know if we like magnitude.)
[218:28] Replace "equal to the original value or closer to
zero than the original value" with
"the value closest to the original value and
no greater in magnitude than the original value"
Alternative: if we don't like magnitude, then:
"the value closest to the original value and no farther
from zero than the original value"
#2 of issue 344:
( Subgroup believes that the UP and DOWN requirements are identical
to the IEEE requirements on IEEE machines; further, with the
above edit, the ZERO requirements are also identical. The COMPATIBLE
requirement is covered normative text. The NEAREST requirement needs
to remain in normative text; the UP and DOWN requirements can be
moved into a note, as can the new ZERO requirement. )
[219:5-7] Delete "UP shall ... zero, and"
(below, editor's choice. I used +INF, -INF, and 0. IEEE standard
uses the infinity symbol for INF and 0 for zero.)
[219:Note 10.13] Add sentence at end of note:
"The I/O rounding modes UP, DOWN, and ZERO have the same effect
as those specified in the IEEE standard for round toward +INF,
round toward -INF, and round toward 0, respectively."
[219] Delete issue 344