Re: How to construct symmetric matrix from just a one half matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg110390] Re: How to construct symmetric matrix from just a one half matrix
- From: "Nasser M. Abbasi" <nma at 12000.org>
- Date: Wed, 16 Jun 2010 05:39:12 -0400 (EDT)
- References: <hv76li$k4j$1@smc.vnet.net>
- Reply-to: nma at 12000.org
On 6/14/2010 11:30 PM, dragec wrote:
> please help me with simple to apply function that will construct
> symmetric matrix from given just a half matrix with diagonal.
> Eg:
>
> From:
> 1 0 0 0
> 2 3 0 0
> 4 9 5 0
> 2 2 3 4
>
> To give:
>
> 1 2 4 2
> 2 3 9 2
> 4 9 5 3
> 2 2 3 4
>
one way:
a = {{1, 0, 0, 0},
{2, 3, 0, 0},
{4, 9, 5, 0},
{2, 2, 3, 4}};
Transpose[LowerTriangularize[a, -1]] + a
{{1, 2, 4, 2},
{2, 3, 9, 2},
{4, 9, 5, 3},
{2, 2, 3, 4}
}
--Nasser