J3/03-146

To: J3
From: UK Fortran panel
Subject: Edits for UK comment MTC8 (IEEE_CLASS_TYPE extension)
Date: 13 March 2003

1. Introduction

Comment MTC8 was

    Add the value IEEE_NOT_IEEE to IEEE_CLASS_TYPE

    This is needed for implementing the module on systems which are
    basically IEEE, but do not implement all of it.  It is analogous to
    IEEE_OTHER for IEEE_ROUND_TYPE. It might be needed, for example, if
    an unformatted file were written in a program executing with
    gradual underflow enabled and read with it disabled.

2. Discussion

The function IEEE_CLASS is prohibited from
(a) returning IEEE_POSITIVE_INF/IEEE_NEGATIVE_INF when IEEE_SUPPORT_INF is
    not true.
(b) returning IEEE_POSITIVE_NAN/IEEE_NEGATIVE_NAN when IEEE_SUPPORT_NAN is
    not true.
(c) returning IEEE_POSITIVE_DENORMAL/IEEE_NEGATIVE_DENORMAL when
    IEEE_SUPPORT_DENORMAL is not true.

Therefore an extra return value is needed to indicate when the argument
value is of a not (fully) supported classification.

3. Edits to 02-007r3

[356:31] Before "." insert ", and IEEE_OTHER_VALUE".
{BTW, the current text is missing the conjunction.}

[363:20-364:1] Replace by

"<<Result Value.>> The result value shall be IEEE_SIGNALING_NAN or
      IEEE_QUIET_NAN if IEEE_SUPPORT_NAN(X) has the value true and the
      value of X is a signaling or quiet NaN, respectively.  The result
      value shall be IEEE_NEGATIVE_INF or IEEE_POSITIVE_INF if
      IEEE_SUPPORT_INF(X) has the value true and the value of X is
      negative or positive infinity, respectively.  The result value
      shall be IEEE_NEGATIVE_DENORMAL or IEEE_POSITIVE_DENORMAL if
      IEEE_SUPPORT_DENORMAL(X) has the value true and the value of X is
      a negative or positive denormalized value, respectively.  The
      result value shall be IEEE_NEGATIVE_NORMAL, IEEE_NEGATIVE_ZERO,
      IEEE_POSITIVE_ZERO, or IEEE_POSITIVE_NORMAL if value of X is
      negative normal, negative zero, positive zero, or positive
      normal, respectively. Otherwise, the result value shall be
      IEEE_OTHER_VALUE."
{We have taken the opportunity to say explicitly that IEEE_QUIET_NAN
is returned for a quiet Nan, etc.}

[364:2+] Add note:
   "NOTE 14.8a. The result value IEEE_OTHER_VALUE is needed for
    implementing the module on systems which are basically IEEE, but do
    not implement all of it. It might be needed, for example, if an
    unformatted file were written in a program executing with gradual
    underflow enabled and read with it disabled."

===END===