What is the first and second index of the gradient tensor

[yuesu jin]

Dear all,

  I want to contract the gradient tensor with another vector, such as T_ij*n_j, the gradient tensor is d_j u_i (d is the partial differential operator). I am wondering what is the first index of gradient tensor, i or j? Thank you !

Best regards,

Yuesu  

--

Yuesu Jin,

Ph.D student,

University of Houston,

College of Natural Sciences and Mathematics,

Department of Earth and Atmospheric Sciences,
Houston, Texas 77204-5008


346-404-2062

[Wolfgang Bangerth]

On 9/7/20 6:21 PM, yuesu jin wrote:
>   I want to contract the gradient tensor with another vector, such as
> T_ij*n_j, the gradient tensor is d_j u_i (d is the partial differential
> operator). I am wondering what is the first index of gradient tensor, i or j?

I believe it is
T_ij = d_j u_i
I know I documented this somewhere (maybe in FEValues::gradient() or
FEValuesView::Vector::gradient) but if you can't find it, it would be nice if
you could just try out and maybe suggest a place where this should be documented.

Best
W.


--
------------------------------------------------------------------------
Wolfgang Bangerth email: bang...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/

[yuesu jin]

Dear Dr.Bangerth,

  I found it just before, it is on  the page of FEValuesView (https://www.dealii.org/current/doxygen/deal.II/classFEValuesViews_1_1Vector.html). Thank you very much!

Best regards,

Yuesu

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