Motion 24,02

[Ulrich Kulisch <Ulrich.Kulisch@xxxxxxxxxxx>]

Dear P1788 members:

Many thanks for all the comments!

It was perhaps a mistake that the text was coupled too much to IEEE 754. 
The motion is not intended to overload IEEE 1788 with complicated 
questions.

I prepared a revised text, see the attachment. The motion is now 
numbered 24.02.

The only concern of the motion is interval arithmetic and simplification 
of its realization. The question is whether the motion is benificial for 
this. The question is not how practical the motion is for existing 
architectures.

I think the old way of IEEE 754, first to set the rounding mode and then 
to call the operation, is well established and motion 24.02 does not 
request its elimination. I see a need for this mechanism as well, in 
particular for those applications where the rounding mode is to be 
selected randomly.

The demand for the 8 operations with the directed roundings is older 
than IEEE 754 arithmetic. At Karlsruhe these operations were realized in 
hardware on an Electrologica X8 already in 1967. Not to require them in 
IEEE 1788 would be fatal for interval arithmetic. The rounding should be 
an integral part of the arithmetic operation. Every one of the 
arithmetic operations with rounding to nearest, downwards or upwards 
should be equally fast. In the end an interval operation should be as 
fast as the corresponding floating-point operation. Modern hardware 
allows this easily.

Best wishes
Ulrich

--
Karlsruher Institut für Technologie (KIT)
Institut für Angewandte und Numerische Mathematik (IANM2)
D-76128 Karlsruhe, Germany
Prof. Ulrich Kulisch

Telefon: +49 721 608-42680
Fax: +49 721 608-46679
E-Mail:ulrich.kulisch@xxxxxxx
www.kit.edu
www.math.kit.edu/ianm2/~kulisch/

KIT - Universität des Landes Baden-Württemberg und nationales Großforschungszentrum in der Helmholtz-Gemeinschaft

Attachment: RoundOper1.pdf
Description: Adobe PDF document