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MathGroup Archive 2005

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Re: tensor product

  • To: mathgroup at smc.vnet.net
  • Subject: [mg61749] Re: [mg61738] tensor product
  • From: Pratik Desai <pdesai1 at umbc.edu>
  • Date: Fri, 28 Oct 2005 03:25:27 -0400 (EDT)
  • References: <200510270954.FAA20757@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

André Hautot wrote:

>In quantum physics one often needs the matrix representation of tensor 
>products
>
>Outer[Times,{{1,2},{3,4}},{{a,b},{c,d}}]//MatrixForm
>
>outputs something like this:
>
>{{{{a,b},{c,d}},{{2a,2b},{2c,2d}},{{{3a,3b},{3c,3d}},{{4a,4b},{4c,4d}}}}
>
>what I need is
>
>{{a,b,2a,2b},{c,d,2c,2d},{3a,3b,4a,4b},{3c,3d,4c,4d}}
>
>How to get this?
>
>Thanks in advance
>
>ahautot at ulg.ac.be
>
>
>
>  
>
How about some thing like this

Clear[a, b, c, d]
mata = {{1, 2}, {3, 4}}
matb = {{a, b}, {c, d}}
Partition[Flatten[Table[Flatten[Outer[Times, mata[[
    s]], matb[[k]]]], {s, 1, 2, 1}, {k, 1, 2, 1}]], 4] // MatrixForm

I am sure there is a more simpler way to doing this

Hope this helps


Pratik .

-- 
Pratik Desai
Graduate Student
UMBC
Department of Mechanical Engineering
Phone: 410 455 8134




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