Diagonal of product of matrices

[robertoam...@gmail.com]

Hello,

I need to compute diag(A*B), where A is nxm and B is mxn. Is there a
way to do it while avoiding the computation of all the non-diagonal
entries of A*B???

Thanks,

Roberto.

[robertoam...@gmail.com]

In general, I need an efficient way to get SOME entries of A*B without
computing the whole product.

Thanks again,

Roberto.

On 20 ene, 17:31, "robertoamaru.cor...@gmail.com"

[robertoam...@gmail.com]

Well, since no one seems to attend this group, I searched the web and
found some nice solutions in

http://www.mathworks.com/matlabcentral/newsreader/view_thread/165784
http://www.mathworks.com/matlabcentral/newsreader/view_thread/168539

I hope this thread be useful for someone in the future...

Thanks anyway,

Roberto.

On 20 ene, 17:36, "robertoamaru.cor...@gmail.com"

[Kevin Sharp]

This can be done easily with a function like this ...


function C = diag_product(A,B )
%DIAG_PRODUCT Return the same as diag(A*B) but without calculating the
whole of A*B
%
C = sum(A .* B', 2);
end


On Jan 23, 7:01 am, "robertoamaru.cor...@gmail.com"

<robertoamaru.cor...@gmail.com> wrote:
> Well, since no one seems to attend this group, I searched the web and
> found some nice solutions in
>

> http://www.mathworks.com/matlabcentral/newsreader/view_thread/165784http://www.mathworks.com/matlabcentral/newsreader/view_thread/168539