J3/06-125
To: J3
From: Michael Ingrassia
Subject: Value of decimal exponent for a real zero value
Date: 2006 January 30
NUMBER: F03/0079
TITLE: Value of decimal exponent for a real zero value
KEYWORDS: Data edit descriptors, Numeric editing, decimal exponent, zero value
DEFECT TYPE: CLARIFICATION/ERRATUM
STATUS: J3 consideration in progress
QUESTION:
In formatted output, what is the value of the
decimal exponent produced for a real zero value
under the D, E, EN, ES, and G edit descriptors?
SUGGESTED ANSWER:
In such a case, the decimal exponent should have
the value zero whether or not a nonzero scale factor
is in effect. Edits are supplied to make this clear.
DISCUSSION:
The Fortran 2003 standard does not specify what the value
of the decimal exponent of a real zero value should be
under formatted output. Every implementation of which Sun
is aware uses the value zero for the decimal exponent
unless a nonzero scale factor is in effect. As a member
of the committee has pointed out, different
implementations format real zeros differently under
nonzero scale factors.
The C and C++ standards both explicitly state that the
value of the decimal exponent produced for the real value
zero under a format that includes an exponent is zero.
The Fortran standard should also.
EDITS:
[227:16+] Add:
(7) On output of a real zero value, the digits in the
exponent field shall all be zero, whether or not
a nonzero scale factor is in effect.
SUBMITTED BY: Michael Ingrassia
HISTORY: J3/06-125 submitted to J3 meeting 175