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Re: Creating a symmetric matrix

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46855] Re: Creating a symmetric matrix
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 12 Mar 2004 02:02:40 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <c2p9ld$dns$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

ll = PadRight[#, 4, 0] & /@ Table[a[j, i], {j, 1, 4}, {i, 1, j}];
ll = ll + MapIndexed[If[Equal @@ #2, 0, #1] & , Transpose[ll], {2}]

??

Regards
  Jens

Mark Coleman wrote:
> 
> Greetings,
> 
> How can I efficiently build a symmetric matrix from an upper triangular
> one, i.e., extract the upper triangular elements and insert them into
> the lower triangle in such a way as to make the resulting square matrix
> symmetric?
> 
> Thanks,
> 
> Mark


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