Empty matrix, scalar, or vector function in loop

Greetings all, I need to write a function called CLF whose input argument is x, that input argument must not have more than two dimensions. If x is an empty array, the function returns -1. If x is a scalar, the function returns 0. If x is a vector, the function returns 1 and if x is none of the above, the function returns 2, do not use isempty, isscalar, isvector, my code is as follows: thank you!

function y=CLF(x)
for a=1:n;
    if x=[];
        y='-1';
    elseif x=a;
        y='0';
    elseif x=[a,a];
        y='1';
    else x~=a;
        y='2';
    end
end
end

Answer 1

[Walter Roberson]

MATLAB uses == for comparisons, not =

Also,

X = []

X =

     []

Y = 1

Y = 1

if X == []; disp('X yes 1'); end
if Y == []; disp('Y yes 1'); end
if isequal(X, []); disp('X yes 2'); end

X yes 2

if isequal(Y, []); disp('Y yes 2'); end

[Walter Roberson]

And remember that your assignment requires you to return a number not a character !

[Lewis HC]

Thank you very much, that was precisely my big doubt in this question, related to scalar

[Walter Roberson]

size([])           %empty

ans = 1×2

0 0

size(ones(0,1))   %empty

ans = 1×2

0 1

size(ones(1,0))  %empty

ans = 1×2

1 0

size(42)               %scalar

ans = 1×2

1 1

size([42, 43, 44])    %row vector

ans = 1×2

1 3

size([42; 43; 44])   %column vector

ans = 1×2

3 1

size([2 3 4; 5 6 7])  %2d array

ans = 1×2

2 3

size(ones(1,2,3))   %3d array

ans = 1×3

1 2 3

size(ones(2,3,4))  %3d array

ans = 1×3

2 3 4

size(ones(1,2,3,0,5,6))  %empty 6d array

ans = 1×6

1 2 3 0 5 6

[Lewis HC]

Thank you dear Walter, at this moment I finished my code, but I think I have a problem with the representation of the vector:

function y=wilo(x)
    if x==[];
        y=-1;
    elseif isequal(x,[]);
        y=-1;
    elseif x==x+1;
        y=0;
    elseif x==[x,x];
        y=1;
    elseif isequal(x,[x,x]);
        y=1;
    else any((x~='[]')&(x~='x+1')&(x~='[x,x]'));
        y=-2;
    end
end

[Walter Roberson]

I missed a case in my examples:

isequal([], ones(1,2,3,0,5,6))

ans = logical
   0

That tells you that you cannot use isequal() to generally detect empty matrices.

elseif x==x+1;

The only case that would match that would be if x consists of all infinite values (positive or negative)

elseif x==[x,x];

[x,x] is going to have more elements than x does, except in the case that x is empty. However we already showed that you cannot use == to test for empty.

You should be examining size(x) rather than any of the tests you are presently doing.

[Lewis HC]

Thank you dear friend!