Re: Matrix Manipulation
- To: mathgroup at smc.vnet.net
- Subject: [mg16461] Re: [mg16389] Matrix Manipulation
- From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
- Date: Sat, 13 Mar 1999 02:22:00 -0500
- Sender: owner-wri-mathgroup at wolfram.com
Here is one easy way do to this. First create the zero 3X3 matrix:
In[34]:=
A=Array[0&,{3,3}];
Next replace the the corresponding part of A by msub:
In[35]:=
A[[{1,3},{1,3}]]=msub;
Now you can simply add A to mm to get what you wanted:
In[36]:=
mm+A
Out[36]//MatrixForm=
22 2 25
4 5 6
30 8 33
On Thu, Mar 11, 1999, Andreas Paul Friedrich Bernhard <bernhard at eng.umd.e
du> wrote:
>I am trying to modify the elements of a submatrix in a matrix, without
>having to replace each element explicitly
>
>for example:
>mm = { {1,2,3}, {4,5,6}, {7,8,9} }
>msub = { {21,22}, {23,24} }
>I now wish to add the sub matrix: to positions (1,1),(1,3),(3,1),(3,3)
>
>I have tried using ReplacePart but it does not recognize the
>multidimensional replacement, I have also tried
>mm[ {{1,3} , {1,3}} ] = mm[ {{1,3} , {1,3}}] + msub
>
>but this crashes horribly
>
>
>Thanks
>AndyIII
>
>--
> -------
>What is man without the beasts, If all the beasts were gone,
>Man would die from great loneliness of Spirit.
>For whatever happens to the beasts, soon happens to man. - Chief Seattle
> -------
>
>****************************************************
>* Andreas P.F. Bernhard *
>* Aerospace Department, University of Maryland *
>* College Park, MD 20742 *
>* bernhard at Glue.umd.edu *
>* Fax: (301) 314-9001, Tel: (301) 405-1141 *
>****************************************************
>
>
>
Andrzej Kozlowski
Toyama International University
JAPAN
http://sigma.tuins.ac.jp/
http://eri2.tuins.ac.jp/