extracting submatrices from cell

Consider the following bit of code:

X={1, 'a'; 'b', 3.14};

X(2,:)

X{2,:}

It produces the following output:

ans = 'b' [3.1400]

ans = b

ans = 3.1400

Can anyone explain to me the reason for the difference. I would have expected the statement X(2,:) to fail and that X{2,:} would have produced what X(2,:) did, in fact, produce.

Answer 1

[Ahmed A. Selman]

Try the same example with:

X={1, 'a'; 'b', 3.14};

K1=X(2,:)

[K21 K22]=X{2,:}

Then use

whos

to see that K1 is a cell, i.e., it only puts part from X into K1, while [K21 K22] is [char double], extracting the contents of the cell into a matrix. The first operation (K1) is another way for cell concatenation.

[Daniel]

Thanks for your answer. So X(2,:) is the same as {X{2,:}}. While I can clearly see this is true, I was hoping to see why this is true. How are

( , )

and

{ , }

defined so that I can predict the outcome of these commands.

[Ahmed A. Selman]

(,) is a portioning, or concatenation process; while

{,} is an extraction, or transformation one .. :)