function [c,ia] = cellsetdiffR2012a(a,b,options)

% 'R2012a' flag implementation

% flagvals = {'rows' 'sorted' 'stable'};

if nargin == 2 

    order = 'sorted'; 

else

    if (options(1) > 0)

        warning(message('MATLAB:SETDIFF:RowsFlagIgnored'));

    end

    if options(3) > 0

        order = 'stable';

    else % if options(2) > 0 || sum(options(2:3)) == 0)

        order = 'sorted';

    end

end 

% Double empties are accepted and converted to empty cellstrs to maintain

% current behavior.

if isequal(class(a),'double') && isequal(a,zeros(0,0)) 

    a = {};

end 

if isequal(class(b),'double') && isequal(b,zeros(0,0)) 

    b = {};

end 

if ischar(a) 

    if isrow(a)

        a = {a};  %refrain from using cellstr to preserve trailing spaces

    else

        a = cellstr(a);

    end

end 

if ischar(b) 

    if isrow(b)

        b = {b};  %refrain from using cellstr to preserve trailing spaces

    else

        b = cellstr(b);

    end

end 

if ~iscellstr(a) || ~iscellstr(b) 

    error(message('MATLAB:SETDIFF:InputClass',class(a),class(b)));

end 

% Determine if A is a row vector.

rowvec = isrow(a); 

% Convert a and b to columns.

a = a(:); 

b = b(:); 

% Make sure a and b contain unique elements. Only get indices if needed.

if nargout <= 1 

    uA = unique(a,order); 

else

    [uA,ia] = unique(a,order);

end 

uB = unique(b,'R2012a'); 

[sortuAuB,indSortuAuB] = sort([uA;uB]); 

% d indicates the location of matching entries

d = find(strcmp(sortuAuB(1:end-1),sortuAuB(2:end)));     

indSortuAuB([d;d+1]) = [];              % Remove all matching entries 

d = indSortuAuB <= length(uA);          % Values in a that don't match. 

if d == 0                   % Force d to be the correct shape when a is  

    d = zeros(0,1);         % cell(0,0) and b is nonempty.

end 

% Find c.

if strcmp(order, 'stable')  

    ndx = sort(indSortuAuB(d));   % Sort indSortuAuB(d) for to maintain 'stable' order.

else 

    ndx = indSortuAuB(d); 

end 

c = uA(ndx); 

% Find ia.

if nargout > 1 

    ia = ia(ndx);

end 

if rowvec 

    c = c.';

end 

end