Cell contents reference from a non-cell array object.

why this error appear "Cell contents reference from a non-cell array object"

U = {} at first

U = TI(s).Si;

TI is strict and Si is a field of TI of cell class

sitem = unique([U{:}]);

[Adam Danz]

U = {};
sitem = unique([U{:}]);

That should not produce an error. The source of the error must be something else or the example isn't accurately reflecting your variables.

[Geoff Hayes]

Mira - U is initialized as a cell array, but then you re-initialize this to whatever Si is

U = TI(s).Si;   

Perhaps you mean to do

U{1} = TI(s).Si;   

[Adam Danz]

Good eye. I missed that.

[Mira le]

I mean U = TI(1).Si I replace s by 1

ans Si ={} is a field of struct TI

for example TI(1).Si= {2 3}

[Adam Danz]

The problem is to the left of the equal sign, not the right. See Geoff's comment again.

[Mira le]

U = TI(s).Si;

it depend on the cells in TI(s).Si

[Adam Danz]

If TI(s).Si isn't a cell, then U won't be a cell, even if you initialize it as a cell

U = {};
U = TI(s).Si; % you're just overwriting U here

If you use Geoff's suggestions, U will remain as cell.

U = {};
U{1} = TI(s).Si;   

[Mira le]

but Si is cell, how it won't be cell

[Adam Danz]

I don't know what your code does. I saw your comment, "for example TI(1).Si= {2 3}" which indicates that Si is a cell array but is that always true? Maybe it is; I don't know.