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## Re: [Getfem-users] specification of Grad expression

 From: Tetsuo Koyama Subject: Re: [Getfem-users] specification of Grad expression Date: Mon, 11 Mar 2019 23:50:34 +0900

P.S. I found mistake in my message.
>In my forecast, the "line" is the direction of variable
Correct word is "row". Sorry for my mistake.

Dear Yves

Thank you very much.

Best Regards,
Tetsuo

>
> Dear Tetsuo,
>
> Yes, in the _expression_ Grad_u * h, h is a direction vector.
>
> Best Regards,
>
> Yves
>
> Le 11/03/2019 à 13:31, Tetsuo Koyama a écrit :
> > Dear Yves
> >
> > I really like the design of regular _expression_.
> > Is h means direction vector?
> > Sorry to ask about such minor details. I just want to be sure.
> >
> > Best Regards,
> >
> > Tetsuo
> >
> > 2019年3月11日(月) 21:08 Yves Renard <address@hidden>:
> >>
> >> Dear Tetsuo,
> >>
> >> It is not easy to find, but the index order in a tensor is shortly
> >> explained in the following part of the documentation :
> >>
> >> http://getfem.org/project/appendixA.html#example-of-elementary-matrix
> >>
> >> For a gradient, each row is the gradient of a component in such a way
> >> that Grad u * h is the derivative in the direction h (so in a sense it
> >> is a derivative)
> >>
> >> Best Regards,
> >>
> >> Yves
> >>
> >>
> >> Le 11/03/2019 à 12:17, Tetsuo Koyama a écrit :
> >>> Dear GetFEM++ Project
> >>>
> >>> Sorry to ask many question.
> >>> When using "Grad_" in regular _expression_ in 3D MeshFem. It seems that
> >>> it create 3D tensor. My question is that the meaning of line and
> >>> column.
> >>> In my forecast, the line is the direction of variable and column is
> >>> the direction of gradient. Is it correct?
> >>> Is there any related part in the document?
> >>> Thank you for reading.
> >>>
> >>> Best Regard Tetsuo.
> >>>
> >> --
> >>
> >>     Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
> >>     INSA-Lyon
> >>     20, rue Albert Einstein
> >>     69621 Villeurbanne Cedex, FRANCE
> >>     http://math.univ-lyon1.fr/~renard
> >>
> >> ---------
> >>
>
> --
>
>    Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
>    INSA-Lyon
>    20, rue Albert Einstein
>    69621 Villeurbanne Cedex, FRANCE
>    http://math.univ-lyon1.fr/~renard
>
> ---------
>