Matrix Extraction based on summation.

Hi.

I have 81*81 matrix. I need to extract a matrix from that, for example of order 81*2, which include two columns i.e. the 34th column and the sum of 22,39 and 59 columns.

I will be really thankful for any suggestion or help. Thanks

Answer 1

[John D'Errico]

Easy peasy.

B = A(:,[34 22 39 59])*[1 0 0 0;0 1 1 1]';