Matlab: how to extract small blocks from large matrix

[confi999]

extract block matlab

Hi,
I have a 24000x24000 sparse matrix. I want to extract 4 blocks out of it;
(0,0) to (6000,6000)
(6001,6001) to (12000,12000)
(12001,12001) to (18000,18000)
(18001,18001) to (24000,24000)

By use of those my aim is to make a block diagonal matrix using matlab command 'blkdiag' .

Can anyone please help me with the matlab code to extract those 4 blocks.
Thank you so much.

 

[hakeen]

large matrices in matlab

Hi

Use simple submatrix operator

e.g. A is 5x5 matrix. A(2:3,4:5) gives 2nd and 3rd rows and 4th and 5th columns. So results is 2x2 matrix. Or you can use A(1:5,1:2) gives 5x2 block extraction.

More details: **broken link removed**

Cheers