Re: Creating a symmetric matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg46870] Re: Creating a symmetric matrix
- From: Paul Abbott <paul at physics.uwa.edu.au>
- Date: Fri, 12 Mar 2004 02:21:50 -0500 (EST)
- Organization: The University of Western Australia
- References: <c2p9ld$dns$1@smc.vnet.net> <c2rne4$p04$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In article <c2rne4$p04$1 at smc.vnet.net>,
Jens-Peer Kuska <kuska at informatik.uni-leipzig.de> wrote:
> 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}]
How about
ll = PadRight[#, 4, 0] & /@ Table[a[j, i], {j, 1, 4}, {i, 1, j}];
ll + Transpose[ll] - DiagonalMatrix[Tr[ll, List]]
instead?
Cheers,
Paul
> 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
>
--
Paul Abbott Phone: +61 8 9380 2734
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