Re: Manipulating a matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg59243] Re: Manipulating a matrix
- From: LBoogie <lwalker701 at earthlink.net>
- Date: Wed, 3 Aug 2005 01:19:47 -0400 (EDT)
- References: <dcmuig$glg$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Ramier wrote:
> I have a n x n matrix and I'd like to remove the first line and the
> first column in order to get the (n-1)x(n-1) matrix with the entries
> remaining. Is there a simple way to do that ?
>
The Submatrix and TakeMatrix functions available in the
LinearAlgebra`MatrixManipulation` package can be used.
Given the following matrix 4x4:
mat = Array[m, {4, 4}]; MatrixForm[mat]
The 3x3 matrix is
TakeMatrix[mat, {2, 2}, {4, 4}]
or you can use
SubMatrix[mat, {2, 2}, {3, 3}]
However, the examples I cited only works when the desired elements of
mat are contiguous.
For the noncontiguous case of removing the second row and column you can use
Drop[Transpose[Drop[mat, {2}]], {2}]
I hope this helps.
LBoogie