Directed rounding

classic Classic list List threaded Threaded
4 messages Options
Reply | Threaded
Open this post in threaded view
|

Directed rounding

Eric Walter
Dear colleagues,

Is it possible to use directed rounding, as made available on all IEEE
747 compliant processors, in gnu-octave? This would help assessing the
number of significant digits in the results of floatting-point computation.

Best regards,

Eric Walter

_______________________________________________
Help-octave mailing list
[hidden email]
https://lists.gnu.org/mailman/listinfo/help-octave
Reply | Threaded
Open this post in threaded view
|

Re: Directed rounding

Oliver Heimlich
On 17.09.2015 18:31, Eric Walter wrote:

> Dear Oliver,
>
> Yes, this might be the way. In MATLAB I got around my rounding problem
> by using Sigfried Rump's interval toolbox INTLAB. Many thanks for your
> suggestion, and thanks to the Octave community for their amazing
> reactivity.
>
> Best regards,
>
> Eric
>

Eric,

you are welcome. Since you know INTLAB, please check whether the free
Octave interval package is a valid replacement for your project. If you
are missing some functionality in the interval package, please let me know.

You can find many functions with directed rounding here (no need to
change the rounding mode yourself):
http://octave.sourceforge.net/interval/function/mpfr_function_d.html

P.S. The Octave interval package is conforming to the IEEE standard for
interval arithmetic. It might behave differently compared to INTLAB,
especially on empty intervals.

Best regards
Oliver

_______________________________________________
Help-octave mailing list
[hidden email]
https://lists.gnu.org/mailman/listinfo/help-octave
Reply | Threaded
Open this post in threaded view
|

Re: Directed rounding

John Swensen-3

On Sep 17, 2015, at 9:47 AM, Oliver Heimlich <[hidden email]> wrote:

On 17.09.2015 18:31, Eric Walter wrote:
Dear Oliver,

Yes, this might be the way. In MATLAB I got around my rounding problem
by using Sigfried Rump's interval toolbox INTLAB. Many thanks for your
suggestion, and thanks to the Octave community for their amazing
reactivity.

Best regards,

Eric


Eric,

you are welcome. Since you know INTLAB, please check whether the free Octave interval package is a valid replacement for your project. If you are missing some functionality in the interval package, please let me know.

You can find many functions with directed rounding here (no need to change the rounding mode yourself):
http://octave.sourceforge.net/interval/function/mpfr_function_d.html

P.S. The Octave interval package is conforming to the IEEE standard for interval arithmetic. It might behave differently compared to INTLAB, especially on empty intervals.

Best regards
Oliver


While most certainly not an Open Source compatible license, INTLAB is open source (small o and s) and free to use excluding only if you are selling a product that uses it. It is free to use, even in commercial setting as long as you aren’t trying to sell a product that includes the code.

As of Octave 3.8, it sounds like INTLAB is fully compatible with Octave.

John S

_______________________________________________
Help-octave mailing list
[hidden email]
https://lists.gnu.org/mailman/listinfo/help-octave
Reply | Threaded
Open this post in threaded view
|

Re: Directed rounding

Eric Walter
Dear John,

INTLAB is no longer available for free, although its cost is still very reasonable. This is no big deal for me as I have access to it and used it in a project that is now finished, namely the writing of a chapter devoted to assessing the accuracy of floatting point computations in a book that has now appeared. I hope many people will get used to the idea of changing rounding mode to see how sensitve their computations are.

Best regards,

Eric



Le 17/09/2015 19:05, John Swensen a écrit :

On Sep 17, 2015, at 9:47 AM, Oliver Heimlich <[hidden email]> wrote:

On 17.09.2015 18:31, Eric Walter wrote:
Dear Oliver,

Yes, this might be the way. In MATLAB I got around my rounding problem
by using Sigfried Rump's interval toolbox INTLAB. Many thanks for your
suggestion, and thanks to the Octave community for their amazing
reactivity.

Best regards,

Eric


Eric,

you are welcome. Since you know INTLAB, please check whether the free Octave interval package is a valid replacement for your project. If you are missing some functionality in the interval package, please let me know.

You can find many functions with directed rounding here (no need to change the rounding mode yourself):
http://octave.sourceforge.net/interval/function/mpfr_function_d.html

P.S. The Octave interval package is conforming to the IEEE standard for interval arithmetic. It might behave differently compared to INTLAB, especially on empty intervals.

Best regards
Oliver


While most certainly not an Open Source compatible license, INTLAB is open source (small o and s) and free to use excluding only if you are selling a product that uses it. It is free to use, even in commercial setting as long as you aren’t trying to sell a product that includes the code.

As of Octave 3.8, it sounds like INTLAB is fully compatible with Octave.

John S


_______________________________________________
Help-octave mailing list
[hidden email]
https://lists.gnu.org/mailman/listinfo/help-octave