Construct a 2D matrix whose each element is the maximum among the receptive elements of multiple 2D matrices constructed by a 3D matrix.

The best way to explain what I'm trying to do is with an example. Say I have the following 2*2*3 matrix.

A(:,:,1) =

    10    20
    20    30

A(:,:,2) =

   100     5
    10    50

A(:,:,3) =

   170    10
   100    12

I want to construct a new 2D matrix (call is Amax) whose every (ith,jth) element is the maximum among the 2D matrices' elements of the original 3D matrix. For the above example, the new matrix Amax should be

Amax =

   170    20
   100    50

Also, I need to know which 3rd dimension of the original 3D matrix the elements in Amax came from. So I need a second 2D matrix (call is INDEX) whose elements are the 3rd dimension of the original 3D matrix. For the above example, the new matrix INDEX should be

INDEX =

     3     1
     3     2

I don't what to use for loops, as the size of my 3D matrix is large. I need to vectorize the above operation.

thank you in advanced Ahmad

Answer 1

[Roger Stafford]

   [B,I] = max(A,[],3);

B gives the 2D matrix of maximums along the third dimension and I gives the corresponding 3rd dimension indices. Read

http://www.mathworks.com/help/matlab/ref/max.html

[Ahmad Abuaish]

Thank you very much Roger for the prompt response. It worked!