MATLAB: MATLAB syntax (parantheses without intermediate steps)

Question

Why is following intermediate calculation step necessary?

temp = abs(rand(10)-eye(10));
result = mean(temp(:));

In Octave is it possible to write the same on one single line:

result = mean(abs(rand(10)-eye(10))(:));

Answer 1

Because to date TMW has chosen to not implement post-addressing expressions on results.

"WHY?" you'd have to ask TMW and it's unlikely they will discuss such internals design decisions/plans publicly.

You can write the expression on one line in MATLAB, too, just more explicitly...

result = mean(mean(abs(rand(10)-eye(10))));  % is one common idiom for 2D arrays

or

result = mean(reshape(abs(rand(10)-eye(10))),:,1);  % is generic