Re: "Built upon 754"

[Ulrich Kulisch <ulrich.kulisch@xxxxxxx>]

Dear John,

interval arithmetic and floating-point arithmetic are distinct calculi. They should be kept stricly separate.
Interval arithmetic developed over the sets R and F of real and floating-point numbers leads to a closed calculus that is totally free of exceptions, i.e., the result of any of the operations plus, minus, multiply, divide and the dot product for intervals of real numbers including elementary functions always delivers a real interval again.
This really is a wonderful and unique result in comparison with conventional floating-point arithmetic with all its exceptions. But I feel that many members of the scientific computing community and even of IEEE 1788 have not yet internalized this.

So I think that idealy the two standards IEEE 754 and IEEE 1788 also should be kept strictly separate. I would even say that any mentioning of  IEEE 754 and its exceptions in IEEE 1788 is a possible source of confusion. If such mentionings  like +0, -0, NaN, IEEE 754 type, IEEE conformant type, and other hints to IEEE 754 would be eliminated in the text of  IEEE 1788 I would fully agree with it.

Best regards
Ulrich




Am 27.01.2016 um 12:53 schrieb John Pryce:

Dear Ulrich

On 27 Jan 2016, at 11:17, Ulrich Kulisch <ulrich.kulisch@xxxxxxx> wrote:

My mail is concerned with the major part of the standard and there is no 
doubt that this is built upon IEEE 754.

I challenge you to quote, by clause and sentence, a single part of 1788 (concept, requirement, operation etc.) that is built upon IEEE 754.

Regards

John Pryce

-- 
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Prof. Ulrich Kulisch

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