In Matlab/Octave, how to do indexing for a transposed matrix?

Question

I create a 3x3 matrix. The indexing operation works well initially.

>> K=rand(3)

K =

    0.8147    0.9134    0.2785
    0.9058    0.6324    0.5469
    0.1270    0.0975    0.9575

>> K(:,1)

ans =

    0.8147
    0.9058
    0.1270

But if I do the indexing operation on the transposed matrix, Matlab throws an error:

>> K'(:,1)
 K'(:,1)
   ↑
Error: Unbalanced or unexpected parenthesis or bracket.
>> (K')(:,1)
 (K')(:,1)
     ↑
Error: Unbalanced or unexpected parenthesis or bracket.

Does anyone have ideas about this?

Answer 1

Do it this way:

K(1,:).'
% note the dot above (.' - means transpose)

% however if you want Hermitian then do this
K(1,:)'
% (just ' - means Hermitian)

% well if K is real then it does not matter

Answer 2

In Octave, you can actually do this.

Note: This does not work in MATLAB

K =

   0.814700   0.913400   0.278500
   0.905800   0.632400   0.546900
   0.127000   0.097500   0.957500

>> (K.')(:,1)
ans =

   0.81470
   0.91340
   0.27850

Answer 3

Simple answer, this syntax isn't allowed (in Matlab, actually it is in Octave as another answer points out). You could do the following though for the same result

K(1,:)'

Or

K = K';
K(:,1)

This won't br too expensive as matlab just flips the indices internally to do the transpose. Like the other answerer states, use .' for complex data or just as a good habit (why mathworks? Why?)