Convertion between empty matrix and Null

I am trying to check if two vectors are identical, quite often these can be null or empty and of different lengths. I confess my ignorance as to the processes which decide wheather the matrix is null or empty, but I am trying to use an all command (the vectors are sorted and have unique elements). I hit a bug when one vector is null and the other Empty. Any ideas?

{strato =

     []

>> stratn

stratn =

   Empty matrix: 1-by-0

>> stratn==stratn

ans =

   Empty matrix: 1-by-0

K>> all(stratn==stratn)

ans =

     1

K>> all(strato==strato)

ans =

     1

K>> all(strato==stratn) ??? Error using ==> eq Matrix dimensions must agree.}

Answer 1

[James Tursa]

Why not use the isequal function?

Answer 2

[Jacob Halbrooks]

It is informative to inspect the dimensions of []:

>> size([])

ans =

       0     0

In equality checks, the dimensions must agree, so this will be unequal to "vector" empties:

>> isequal(ones(0,0), ones(0,1))

ans =

       0

I would suggest you use ISEMPTY if you want to treat all empties as the same:

>> isequal(isempty(ones(0,0)), isempty(ones(0,1)))

ans =

       1

Answer 3

[Walter Roberson]

A matrix is empty if any of its dimensions are 0.

See also isempty()

[Langyu]

Thanks, I think this answer works best.

Answer 4

[Sean Danaher]

many thanks to James and also Jacob with a more comprehensive answer