[std-interval] Discontinuity flag

George Corliss George.Corliss at marquette.edu
Mon Oct 2 06:50:16 PDT 2006

Walter, Juergen, and Guillaume,

The endorsement of the GAMM activity group is most welcome.

I support your discontinuous flag.

Dr. George Corliss
Electrical and Computer Engineering
Marquette University
P.O. Box 1881
1515 W. Wisconsin Ave.
Milwaukee, WI 53201-1881
George.Corliss at Marquette.edu
414-288-6599 (office); 288-4400 (GasDay);
    288-6280 (Dept.); 288-5579 (fax)
Office: Haggerty Engineering 296

On 10/2/06 2:14 AM, "Prof.Dr.J.Wolff von Gudenberg"
<wolff at informatik.uni-wuerzburg.de> wrote:

> Dear Intervalers,
>  during the SCAN 2006 meeting in Duisburg the following points have been
> discussed.
> The GAMM activity group for Computer Arithmetic and Scientific Computing
> strongly supports the efforts to standardize
> interval arithmetic in C++
> The discussion showed that
> Standard functions MUST set a flag when the argument interval is not
> completely contained in the domain of the function
> Otherwise (i.e without the flag) verification of the result with fixed
> points or other assertions that need continuity is not possible
> A whole branch of interval arithmetic will not be supported by the
> standard in that case.
> We propose (together with G. Melquiond) That this flag can be managed by
> the user himself.
> The elementary functions (at least those with bounded domain) have to
> set this flag in the case
> when the argument interval is not completely contained in the domain of
> the function
> interval<T> sqrt ( interval<T> x, bool& flag)
> will be a proper interface
> Such a function is also necessary for the division operator
> interval<T> divide ( interval<T> x, interval<T> y, bool& flag)
> interval<T> divide ( T x, interval<T>y,  bool& flag)
> multiplication and addition are ok.
> Walter Kraemer
> Juergen Wolff v Gudenberg
> _______________________________________________
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> Std-interval at compgeom.poly.edu
> http://compgeom.poly.edu/mailman/listinfo/std-interval

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