[Scilab-users] ?==?utf-8?q? ?==?utf-8?q? ?= {EXT} need a more efficient and faster code: suggestions welcom

[Antoine Monmayrant]

Argh, OK, I get it: scilab treats A.^2 exactly like A.^%pi and not like "square it".
Makes sense, thank you for the info.
I wonder how julia is performing with respect to A.^2 compared to A.*A...

Antoine
 
 
Le Mercredi, Janvier 31, 2018 11:30 CET, Stéphane Mottelet <stephane.mottelet at utc.fr> a écrit: 
 
> I am an old school guy and have learned scientific computing with 
> Fortran... Using mutiplication instead of power elevation is an old 
> trick which should not be necessary with a more clever interpreter 
> (which should detect that 2 is actually a (small) integer and use 
> multiplication instead)
> 
> S.
> 
> Le 31/01/2018 à 11:22, Antoine Monmayrant a écrit :
> > Hello Stéphane,
> >
> > Sorry to hijack the discussion but I didn't know that there was such a difference between A.*A and A.^2.
> > Could you tell us more about it?
> > Why is is twice faster to use the A.*A form?
> > Is this documented somewhere?
> >
> > Cheers,
> >
> > Antoine
> >   
> >   
> > Le Mercredi, Janvier 31, 2018 10:53 CET, Stéphane Mottelet <stephane.mottelet at utc.fr> a écrit:
> >   
> >> Replacing
> >>
> >>       MinDist=[MinDist sqrt(min(sum(DIFF.^2,2)))];
> >>
> >> by
> >>
> >>       MinDist=[MinDist sqrt(min(sum(DIFF.*DIFF,2)))];
> >>
> >> will be at least twice faster. Crunching elapsed time could be done by
> >> using parallel_run (with 5.5.2 version) if you have a multi-core processor.
> >>
> >> S.
> >>
> >> Le 31/01/2018 à 09:36, Dang Ngoc Chan, Christophe a écrit :
> >>> Hello,
> >>>
> >>> The following suggestions will probably not have a drastic influence
> >>> (I don't see how it could be more vectorised)
> >>> but his a little thing I see:
> >>>
> >>>> De : users [mailto:users-bounces at lists.scilab.org] De la part de Heinz Nabielek
> >>>> Envoyé : mercredi 31 janvier 2018 00:13
> >>>>
> >>>>      MinDist=[MinDist sqrt(min(sum(DIFF.^2,2)))];
> >>> Maybe you could concatenate the squares of the distance
> >>> and then compute the square root of the whole vector in the end:
> >>>
> >>> sqMinDist=[sqMinDist min(sum(DIFF.^2,2))];
> >>>
> >>> …
> >>>
> >>> end
> >>>
> >>> …
> >>>
> >>> MinDist = sqrt(sqMinDist)
> >>>
> >>> Hope this helps,
> >>>
> >>> Regards
> >>>
> >>> --
> >>> Christophe Dang Ngoc Chan
> >>> Mechanical calculation engineer
> >>> This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error), please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
> >>> _______________________________________________
> >>> users mailing list
> >>> users at lists.scilab.org
> >>> http://lists.scilab.org/mailman/listinfo/users
> >>
> >> -- 
> >> Stéphane Mottelet
> >> Ingénieur de recherche
> >> EA 4297 Transformations Intégrées de la Matière Renouvelable
> >> Département Génie des Procédés Industriels
> >> Sorbonne Universités - Université de Technologie de Compiègne
> >> CS 60319, 60203 Compiègne cedex
> >> Tel : +33(0)344234688
> >> http://www.utc.fr/~mottelet
> >>
> >> _______________________________________________
> >> users mailing list
> >> users at lists.scilab.org
> >> http://lists.scilab.org/mailman/listinfo/users
> >>
> > _______________________________________________
> > users mailing list
> > users at lists.scilab.org
> > http://lists.scilab.org/mailman/listinfo/users
> 
> 
> -- 
> Stéphane Mottelet
> Ingénieur de recherche
> EA 4297 Transformations Intégrées de la Matière Renouvelable
> Département Génie des Procédés Industriels
> Sorbonne Universités - Université de Technologie de Compiègne
> CS 60319, 60203 Compiègne cedex
> Tel : +33(0)344234688
> http://www.utc.fr/~mottelet
> 
> _______________________________________________
> users mailing list
> users at lists.scilab.org
> http://lists.scilab.org/mailman/listinfo/users
>