Subject: WG11/N342: Information to NBs on LIA-1 ballot

From: Willem Wakker <[email-masked]>
Date: Tue, 03 Nov 92 15:36:11 N

SC22/WG11/N342

From:	     ISO/IEC JTC1/SC22/WG11
To:	     SC22 Member bodies
Subject:     Request for clear national body positions in the voting on
	     ISO CD 10967-1 Language-Independent Arithmetic
	     Part 1: Integer and Real Arithmetic
Reference:   SC22/N1263
Date:	     October 1992

The intention of the Language-Independent Arithmetic
standards is to provide a family of standards which can be
normatively included by reference in programming language
standards to define the required properties of mathematical
operations and functions.  The required properties are so
defined as to afford the numerical programmer some
assurances and quantitative measures of the behavior of the
programming language operations as compared to the true
mathematical operations on a wide range of machine
architectures.

Language standards have been reluctant to standardize in
this area because of a concern that such standardization
would limit the platforms on which an efficient conforming
implementation could be built.	This is a valid concern, but
the effect has been to make arithmetic in programming
languages almost entirely "implementation-dependent", i.e.
defined as whatever the compiler/platform does.  This
standard seeks to make arithmetic at least "implementation-
defined", i.e. documented choices from a list of
alternatives, supported by some corresponding parameter
values whose meaning is described by the standard.

ISO CD 10967-1 (Language-independent arithmetic, Part 1
Integer and real arithmetic) is a specification for
conformance of arithmetic software which can be achieved on
a wide range of machine architectures.	This contrasts with
IEC 559:1989 (Binary floating-point arithmetic for
microprocessor systems), better known as IEEE 754, which is
a specification for the implementation of arithmetic and is
only practical if implemented in hardware.

There is an outspoken group of numeric users who strongly
believe

  1.  that IEC 559:1989 should be the only standard for
      arithmetic; and

  2.  that ISO CD 10967-1 "condones weaker machine
      arithmetics" and thus "conflicts with" and
      "undermines" IEC 559; and

  3.  there is no useful goal of ISO CD 10967-1 which cannot
      be met by simply citing IEC 559.

These users fear that vendors will continue the development
of alternate (they would say "inferior") arithmetics and
cite compliance with ISO 10967-1 as an alternative to
complying with IEC 559.  Even worse, de jure standards and
procurements might cite ISO 10967-1 rather than IEC 559,
thereby permitting the acquisition of equipment with
arithmetic "inadequate for serious numerical analysis".  As
a consequence they do not want to see CD 10967-1 progressed
AT ALL.  Comments generated by this community cite dozens of
supposed problems and weaknesses in the draft standard.  It
is the impression of the Working Group, however, that their
purpose is not to improve the standard; their purpose is to
prevent its progression.  To be acceptable to this body of
commentators, CD 10967-1 would have to be recast as a
binding of IEC 559 to programming languages and require
conformance of arithmetic operations in the languages to IEC
559.

Experience in some language working groups teaches that such
a requirement would prevent the normative inclusion of ISO
10967-1 in language standards and thus DEFEAT ITS PURPOSE.
Arithmetic in programming languages would remain
implementation-defined, as now, with some implementations
conforming to IEC 559, and many others unable to.

SC22/WG11 therefore asks SC22 member bodies voting on the
progression of CD 10967-1 to make a careful determination of
what the national body position on this issue is:

   - Is it the position of the national body that this
     document should not be progressed because of a
     perceived conflict with the aims of IEC 559?

   - Or is it the position of the national body that the
     document should be progressed, while possibly citing
     certain technical problems which require resolution?

If a sufficient number of national bodies hold the first
position, then the Working Group will not be able to resolve
the NO-votes and the standardization effort for LIA Part 1
will have to be abandoned.  If, on the other hand, all
national bodies hold the second position, then the Working
Group will make every effort to resolve the ballot comments
in a way satisfactory to all national bodies, so that
consensus on progression of the document can be obtained.

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Willem Wakker					 email: <[email-masked]>
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