question regarding the cellfun function in MATLAB.

When / why should I use it, and when may I just as well drop it?

A simple example: Let's say I have a cell a, and I want to find the average of all values in a. 

a{1} = [1 2;3 4]; a{2} = [1 2 3;4 5 6; 7 8 9];

My approach would be something like: 

mean([a{1}(:); a{2}(:)])

What will the appropriate cellfun version of this be, and is it any better?

I've tried doing something like this, (obviously not working): 

mean_a = mean(cellfun(@mean, a,'UniformOutput',0))

Thanks! 

Answers: 

cellfun is just like looping through the cell matrix and
executing specified function separately on each cell.
It's usually faster than doing the same thing explicitly
in loop, but the basic difference is that its easy to
write and read - its immediately clear what the call is
doing. But you could just as well write the loop yourself.

In your specific case you could use cellfun this way: 

mean_a = mean(cellfun(@(x) mean(x(:)), a));

If you have thousands of cells and you want to do something
to each of them you either use a loop or a cellfun
BTW: @(x) means that you want the content of each cell
to be understood as x so that mean(x(:)) gives you what
you want - mean of the whole matrix content of the cell.