Understanding why I can't use index on the result of the size function on a matrix in matlab

Question

When trying:

a = [ 1 1 ; 1 1 ];
size(a)(1)

I get

Error: ()-indexing must appear last in an index
expression

M

Answer 1

Because you can't index the result of a function like that in MATLAB without creating a temporary.

temp = size(a);
temp(1)

will work. There are often other ways of getting what you want, however. In your example, you can make use of the dim argument in the function size(X,dim):

size(a,1)

That will get you the size of the first dimension directly, avoiding the need to create a temporary variable.