12-154
To: J3
From: Robert Corbett
Subject: Interp request: Are IEEE +0 and -0 distinguished
Date: 2012 June 11

----------------------------------------------------------------

NUMBER: F08/????
TITLE: Are the IEEE values +0 and -0 distinguished
KEYWORDS: IEEE, zero, IEEE_SUPPORT_DATATYPE
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

Suppose the value of IEEE_SUPPORT_DATATYPE is true for
arguments of some kind type parameter values for a
processor.  Is the processor required to distinguish between
the real values +0 and -0 if the kind type parameter value of
those zeros is among the kind type parameter values for which
IEEE_SUPPORT_DATATYPE is true?

ANSWER:

The processor is required to distinguish between +0 and -0
if IEEE_SUPPORT_DATATYPE is true for arguments that have the
same kind type parameter value as the zeros.  If the value
of the function IEEE_SUPPORT_DATATYPE is true for an argument,
the function IEEE_COPY_SIGN must be defined for values with
the same kind type parameter value as the
argument (14.9, 406:17-18 and 14.11.24, 417:13-15).  The
function IEEE_COPY_SIGN is required to distinguish between
+0 and -0 when they appear as the second
argument (14.11.3, 409:6).

EDITS:

None.

SUBMITTED BY: Robert Corbett

HISTORY: 12-xxx    m198  Submitted