Re: Assignment to submatrices
- To: mathgroup@smc.vnet.net
- Subject: [mg11339] Re: Assignment to submatrices
- From: Allan Hayes <hay@haystack.demon.co.uk>
- Date: Fri, 6 Mar 1998 00:40:58 -0500
- References: <6dg8no$2up@smc.vnet.net>
David E. Cox wrote:
> Is there any way to assign directly to submatrices, without building a
> higher order tensor? ie if A and B are 2x2's how do I create the 4x4
> matrix [0 I2x2; A B].
Dave,
The Add-on LinearAlgebra`MatrixManipulation` does the job.
In[1]:=
A= Array[a,{2,2}];
In[2]:=
B = Array[b,{2,2}];
In[3]:=
I22 =IdentityMatrix[2];
In[4]:=
Z=0 I22;
In[5]:=
<<LinearAlgebra`MatrixManipulation`
In[6]:=
BlockMatrix[{{Z,I22},{A,B}}]//MatrixForm
Out[6]//MatrixForm=
0 0 1 0
0 0 0 1
a[1, 1] a[1, 2] b[1, 1] b[1, 2]
a[2, 1] a[2, 2] b[2, 1] b[2, 2]
--
Allan Hayes
Training and Consulting
Leicester, UK
hay@haystack.demon.co.uk
http://www.haystack.demon.co.uk
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