How to turn certain parts/blocks of a large matrix to zero while keeping the rest of the original matrix intact?

Hi. I have a large weighted matrix, about 1000*7000 order. I need to turn certain blocks of this matrix (with known range of rows and columns) to zero, while keeping the rest of the matrix intact.

Any help will be highly appreciated.

Best regards, Shafique

Answer 1

[the cyclist]

 a = rand(1000,7000); % This represents your input array
 a(1:3,6:9) = 0; % This zeros out the first three rows of columns 6 through 9.
 a(1:10,1:10) % This shows the upper left corner of the array, to illustrate the zeroed out area.

[Muhammad Shafique]

Thanks a lot.