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Re: Manipulating a matrix

  • To: mathgroup at smc.vnet.net
  • Subject: [mg59248] Re: [mg59212] Manipulating a matrix
  • From: Sseziwa Mukasa <mukasa at jeol.com>
  • Date: Wed, 3 Aug 2005 01:19:51 -0400 (EDT)
  • References: <200508020442.AAA16742@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On Aug 2, 2005, at 12:42 AM, Ramier wrote:

> Hello everyone,
>
> I think that my question is rather simple and maybe I ought to go
> deeper into Mathematica book:
> 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 ?

Hear are three suggestions, if you use the Help Browser it will point  
you to the relevant sections of the Mathematica Book.

Supposing that the matrix is in a then:

Rest/@Rest[a]

a[[Range[2,n],Range[2,n]]]

and

<<LinearAlgebra`MatrixManipulation`
TakeColumns[TakeRows[a,1-n],1-n]

are all equivalent to taking the n-1xn-1 matrix formed by removing  
the first row and column.

>
> Perhaps my question is really simple or idiot but I've never used
> Mathematica before.

We all had to learn at some point.

Regards,

Ssezi


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