How to find the indices within a matrix where its elements are identical along the third dimension

Hi all,

I am scratching my head to determine a way where I can find the indices within a multi-dimensional matrix where its elements are identical (i.e. equal) along the third dimension.

In specific I have a multi-dimensional matrix:

M = rand(100,100,3) ;

Lets say somewhere in that matrix, along the third dimension we have some elements that are equal, which we would be able to identify with the following way.

idx = M(:,:,1) == M(:,:,2) & M(:,:,2) == M(:,:,3) ;

Admitedly, the above would give me what I want but when the third dimension becomes much greater than 3 (as it does in my case), it becomes quite cumbersome to code. I would therefore appreciate your help with this.

Regards

KMT.

Answer 1

[Matt J]

idx = all( M==M(:,:,1) , 3);

[KostasK]

Nice one!