Find zeros in a part of a matrix

Hi all,

I have a matrix such that:

 Tarr =

   1.0e+05 *

    0.0006    0.0000    0.0000    0.0000         0
    0.0002         0         0         0         0
    0.0001         0         0         0    0.0001
    0.0004         0         0         0         0
         0    1.3018    1.4506    0.2323    0.0540
    0.0005    0.0000    0.0000         0         0
    0.0002         0         0         0         0
    0.0000         0         0         0         0
    0.0004         0         0         0         0
         0   -2.9018   -3.0506    0.2323    0.0540
    0.0005         0         0         0         0
    0.0002         0         0         0         0
    0.0000         0         0         0         0
    0.0004         0         0         0         0
         0         0         0    0.2323    0.0540

I would like to find the indices of the zero elements in the following subsection of the matrix

 Tarr(5:5:end,2:end)

An then replace those with some numbers I desire. I know this must be fairly easy, however I cant seem to be able to find a straightforward way.

KR,

KMT.

Answer 1

[Jos (10584)]

temp = Tarr(5:5:end,2:end) ;  % get the relevant portion
temp(temp==0) == 12345 ;      % your value
Tarr(5:5:end,2:end) = temp ;  % put the edited portion back in

[Konstantinos Tsitsilonis]

It works nicely thanks!