Operands to the || and && operators

Hi,

I am getting this massage: Operands to the and && operators must be convertible to logical scalar values.

Error in main (line 27) elseif model==2 model==3

what does this mean please regards

Answer 1

[Steven Lord]

In the expression X && Y or X || Y, X and Y must both be scalar (as defined by isscalar, meaning the values have size [1 1]) and the commands logical(X) and (if necessary) logical(Y) must succeed.

Cases that will not work:

% X is not scalar
[1 2] && 1
[] && 1

% X cannot be converted to a logical
NaN && 5

Cases that will work:

% Both scalar, both convertible to logical
1 && 0
true && true

% X causes the comparison to short-circuit so Y is not checked
false && [1 2] % false AND anything is false
true || NaN % true OR anything is true