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Re: Tensor cross vector

  • To: mathgroup at smc.vnet.net
  • Subject: [mg115467] Re: Tensor cross vector
  • From: solid-state <phmech at gmail.com>
  • Date: Tue, 11 Jan 2011 19:23:05 -0500 (EST)
  • References: <ig97pu$1ro$1@smc.vnet.net> <igbndm$hd9$1@smc.vnet.net>

On Jan 9, 10:17 am, Peter Breitfeld <ph... at t-online.de> wrote:
> solid-state wrote:
> > Hi, everybody!
>
> > Could anybody please help me on how to find a tensor-vector cross
> > product? The "Cross" function seems to work only with vectors. Thanks.
>
> Do you intend something like this:
>
> tensorCross[u_?VectorQ,m_?MatrixQ]:=
> Transpose[Table[Cross[u,Transpose[m][[k]]],{k,Length[u]}]]
>
> tensorCross[m_?MatrixQ,u_?VectorQ]:=
>   Table[Cross[m[[k]],u],{k,Length[u]}]
>
> (ten = Array[Subscript[a, ##] &, {3, 3}]) //MatrixForm
> vek = Array[Subscript[x, #] &, {3}]
>
> tensorCross[vek, ten] // MatrixForm
>
> tensorCross[ten, vek] // MatrixForm
>
> --
> _________________________________________________________________
> Peter Breitfeld, Bad Saulgau, Germany --http://www.pBreitfeld.de

Oh, yeah, thank you very much, Peter! That is exactly what I meant.
I first did it in two steps: by breaking (manually) my matrix into
rows, then finding a cross product of them with my vector (with the
help of the standard "Cross" function) and then using Mathematica's
"Join" function to form the resulting matrix. But I was looking for
such a way of doing this, that would work without my manual
intervention, so in this way you helped me a lot!


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