minimum element of each matrix belonging to a 4d matrix

I have a 4D matrix which you can think of as an array of matrices. How do i find the minimum value of each matrix ?

Answer 1

[the cyclist]

You don't specify which dimension hold the matrices you want to get the minimum values of. However, you should be able to get the idea for an algorithm from this. You just have to properly reshape (and possibly shift some dimension around using permute) to line up the values you want the minimum of.

% Some pretend data
M = rand(2,3,4,5)

% Supposing I don't know the size, I get it
S = size(M)

% Reshape such that each array is now a column
R = reshape(M,prod(S(1:3)),[]);

% Get the minimum values
V = min(R)

[Walter Roberson]

You do not need to do that all that work. If you want to take the minimum along the N'th dimension then

N = 3;   %for example
V = squeeze( min(YourMatrix, [], N) );

[RuiQi]

Thanks ! I managed to get it to work but I found reshape easier to understand

[the cyclist]

Walter, the reason he does need to do at least some of that work is that he is not taking a min along a dimension, but rather wants the minimum of a series of matrices. So, he needs to reshape those matrices into their own single dimension. (My answer didn't illustrate that well, but seems like he figured it out.)