IEEE 754R minutes from 16 October, 2003


Note taker: Jeff Kidder, Intel Corporation

[These are my raw notes. Please send any substantive corrections or omissions. Thanks.]

October meeting 10/16/2003:


Draft Review Highlights

Format items to get addressed

The Tower of Precision - higher accuracy, or larger values in a standard way
Is there a standard problem to solve? Can we make sensible definitions.
What is the radix? 2 or 10
What is the precision?
What is the exponent range?
Some want to specify bit patterns.
[There was a discussion of the demand and plausibility of their use.]
David Baily's package supports unpredictable amounts of precision. Example: Semetrical Level Index -- extreme example of diversity. Dave will propose a paragraph on formats.

Get shared data formats out of 1596.5(1993) into one place

Down to 4 pages.
Do we want to introduce into the standard translation from DEC VAX FP into 754.
A: Historical FP formats
B: Integer formats 10.1-10.3
C: Big vs Little endian
Do we want to describe historical FP? Cray / VAX / CVC / NEC / MS FP / HP 3000
Shouldn't this just be published in the anals of computer history. IEEE 754r should be complete in and of itself. What do we do with 1596? We would prefer to see this historical info just available on the web, or just republish the spec.

Standardized transcendental functions

There are algorithms which are reasonably fast in the nominal case which do correctly rounded. Java has math and strict-math libraries. If you want reproducible versions, you use strict-math. They are defined procedurally. There are two kinds of performance penalty:
One: Can you figure out if it is correctly rounded
Two: If it isn't, you have extra work to do (upsetting vector computations)
Have considered "levels of accuracy". Can't specify meaningful way to specify lesser accuracy in a testable way, and in a way that maintains expected properties of the function (monotonicity, symmetry, ...). "Each transcendental function costs somebody's lifetime to understand."
Committee opinion: It is too soon to do this.


Next time: Tue 11/11 & Wed 11/12
* Short Draft Review
* State
* Testing
Looking for a volunteer for a standard implementation
Looking for a test suite
[Or funding for graduate students to do the work...]
* What to do about NaNs

December: Wed 12/10 & Thurs 12/11
* Speaker on testing

754 | revision | FAQ | references