How to compare a matrix element with its neighbours without using a loop in MATLAB?

Question

I have a matrix in MATLAB. I want to check the 4-connected neighbours (left, right, top, bottom) for every element. If the current element is less than any of the neighbours the

Answer 1

If you have the image processing toolbox, you can do this with a morpological dilation to find local maxima and suppress all other elements.

array = magic(6); %# make some data

msk = [0 1 0;1 0 1;0 1 0]; %# make a 4-neighbour mask

%# dilation will replace the center pixel with the 
%# maximum of its neighbors
maxNeighbour = imdilate(array,msk);

%# set pix to zero if less than neighbors
array(array

edited to use the same data as @gnovice, and to fix the code