Re: matrix manipulation

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• Subject: [mg132402] Re: matrix manipulation
• From: Itai Seggev <itais at wolfram.com>
• Date: Mon, 10 Mar 2014 04:37:13 -0400 (EDT)
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• References: <20140308074331.2B3106A1D@smc.vnet.net>

```On Sat, Mar 08, 2014 at 02:43:31AM -0500, dimanag78 at gmail.com wrote:
> Hello to all.
>
> I have the following 6x6 matrix
>
> Table[Subscript[C, k, j][i], {k, 1, 6}, {j, 1, 6}]
>
> I want this matrix to be symmetric, that is,
> Subscript[C, k, j][i] = Subscript[C, j, k][i] for j != k.
>
> In other words I want the matrix
>
> {{Subscript[C, 1, 1][i], Subscript[C, 1, 2][i], Subscript[C, 1, 3][i],
>    Subscript[C, 1, 4][i], Subscript[C, 1, 5][i],
>   Subscript[C, 1, 6][i]}, {Subscript[C, 1, 2][i],
>   Subscript[C, 2, 2][i], Subscript[C, 2, 3][i], Subscript[C, 2, 4][i],
>    Subscript[C, 2, 5][i],
>   Subscript[C, 2, 6][i]}, {Subscript[C, 1, 3][i],
>   Subscript[C, 2, 3][i], Subscript[C, 3, 3][i], Subscript[C, 3, 4][i],
>    Subscript[C, 3, 5][i],
>   Subscript[C, 3, 6][i]}, {Subscript[C, 1, 4][i],
>   Subscript[C, 2, 4][i], Subscript[C, 3, 4][i], Subscript[C, 4, 4][i],
>    Subscript[C, 4, 5][i],
>   Subscript[C, 4, 6][i]}, {Subscript[C, 1, 5][i],
>   Subscript[C, 2, 5][i], Subscript[C, 3, 5][i], Subscript[C, 4, 5][i],
>    Subscript[C, 5, 5][i],
>   Subscript[C, 5, 6][i]}, {Subscript[C, 1, 6][i],
>   Subscript[C, 2, 6][i], Subscript[C, 3, 6][i], Subscript[C, 4, 6][i],
>    Subscript[C, 5, 6][i], Subscript[C, 6, 6][i]}}
>
>
> Thank you very much, in advance, for yor help.

SymmetrizedArray[j_ :> Subscript[C, Sequence @@ j][i], {6, 6},
Symmetric[{1, 2}]]

If you really want it as a list of lists, you can use

Normal @ SymmetrizedArray[j_ :> Subscript[C, Sequence @@ j][i], {6, 6},
Symmetric[{1, 2}]]
--
Itai Seggev
Mathematica Algorithms R&D
217-398-0700

```

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