function [lia,locb] = ismember(A,B,flag1,flag2)

%ISMEMBER True for set member.

%   LIA = ISMEMBER(A,B) for arrays A and B returns an array of the same

%   size as A containing true where the elements of A are in B and false

%   otherwise.

%

%   LIA = ISMEMBER(A,B,'rows') for matrices A and B with the same number

%   of columns, returns a vector containing true where the rows of A are

%   also rows of B and false otherwise.

%

%   [LIA,LOCB] = ISMEMBER(A,B) also returns an array LOCB containing the

%   lowest absolute index in B for each element in A which is a member of

%   B and 0 if there is no such index.

%

%   [LIA,LOCB] = ISMEMBER(A,B,'rows') also returns a vector LOCB containing

%   the lowest absolute index in B for each row in A which is a member

%   of B and 0 if there is no such index.

%

%   The behavior of ISMEMBER has changed.  This includes:

%     -	occurrence of indices in LOCB switched from highest to lowest

%     -	tighter restrictions on combinations of classes

%

%   If this change in behavior has adversely affected your code, you may 

%   preserve the previous behavior with:

%

%      [LIA,LOCB] = ISMEMBER(A,B,'legacy')

%      [LIA,LOCB] = ISMEMBER(A,B,'rows','legacy')

%

%   Examples:

%

%      a = [9 9 8 8 7 7 7 6 6 6 5 5 4 4 2 1 1 1]

%      b = [1 1 1 3 3 3 3 3 4 4 4 4 4 9 9 9]

%

%      [lia1,locb1] = ismember(a,b)

%      % returns

%      lia1 = [1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 1 1]

%      locb1 = [14 14 0 0 0 0 0 0 0 0 0 0 9 9 0 1 1 1]

%

%      [lia,locb] = ismember([1 NaN 2 3],[3 4 NaN 1])

%      % NaNs compare as not equal, so this returns

%      lia = [1 0 0 1], locb = [4 0 0 1]

%

%   Class support for inputs A and B, where A and B must be of the same

%   class unless stated otherwise:

%      - logical, char, all numeric classes (may combine with double arrays)

%      - cell arrays of strings (may combine with char arrays)

%      -- 'rows' option is not supported for cell arrays

%      - objects with methods SORT (SORTROWS for the 'rows' option), EQ and NE

%      -- including heterogeneous arrays derived from the same root class

%

%   See also ISMEMBERTOL, INTERSECT, UNION, UNIQUE, UNIQUETOL, SETDIFF,

%            SETXOR, SORT, SORTROWS.

%   Copyright 1984-2018 The MathWorks, Inc.

% Convert string flags to char flags to dispatch to the right method

if (nargin == 3) && isstring(flag1) 

    flag1 = convertFlag(flag1);

    [lia, locb] = ismember(A, B, flag1);

    return;

end

if (nargin == 4) && (isstring(flag1) || isstring(flag2)) 

    if isstring(flag1)

        flag1 = convertFlag(flag1);

    end

    if isstring(flag2)

        flag2 = convertFlag(flag2);

    end

    [lia, locb] = ismember(A, B, flag1, flag2);

    return;

end

if (isstring(A) || isstring(B)) 

    if ~ischar(A) && ~iscellstr(A) && ~isstring(A)

        firstInput = getString(message('MATLAB:string:FirstInput'));

        error(message('MATLAB:string:MustBeCharCellArrayOrString', firstInput));

    elseif ~ischar(B) && ~iscellstr(B) && ~isstring(B)

        secondInput = getString(message('MATLAB:string:SecondInput'));

        error(message('MATLAB:string:MustBeCharCellArrayOrString', secondInput));

    end

    A = string(A);

    B = string(B);

end

if nargin <= 2 

    if nargout < 2 

        lia = ismemberR2012a(A,B); 

    else

        [lia,locb] = ismemberR2012a(A,B);

    end 

else

    % acceptable combinations, with optional inputs denoted in []

    % ismember(A,B, ['rows'], ['legacy'/'R2012a'])

    nflagvals = 3;

    flagvals = ["rows", "legacy", "R2012a"];

    % When a flag is found, note the index into varargin where it was found

    flaginds = zeros(1,nflagvals);

    for i = 3:nargin

        if i == 3

            flag = flag1;

        else

            flag = flag2;

        end

        assert(~isstring(flag));

        foundflag = matlab.internal.math.partialMatchString(flag,flagvals);

        if ~any(foundflag)

            if ischar(flag)

                error(message('MATLAB:ISMEMBER:UnknownFlag',flag));

            else

                error(message('MATLAB:ISMEMBER:UnknownInput'));

            end

        end

        % Only 1 occurrence of each allowed flag value

        if flaginds(foundflag)

            error(message('MATLAB:ISMEMBER:RepeatedFlag',flag));

        end

        flaginds(foundflag) = i;

    end

    % Only 1 of each of the paired flags

    if flaginds(2) && flaginds(3)

        error(message('MATLAB:ISMEMBER:BehaviorConflict'))

    end

    % 'legacy' and 'R2012a' flags must be trailing

    if flaginds(2) && flaginds(2)~=nargin

        error(message('MATLAB:ISMEMBER:LegacyTrailing'))

    end

    if flaginds(3) && flaginds(3)~=nargin

        error(message('MATLAB:ISMEMBER:R2012aTrailing'))

    end

    if flaginds(3) % trailing 'R2012a' specified

        if nargout < 2

            lia = ismemberR2012a(A,B,logical(flaginds(1)));

        else

            [lia,locb] = ismemberR2012a(A,B,logical(flaginds(1)));

        end

    elseif flaginds(2) % trailing 'legacy' specified

        if nargout < 2

            lia = ismemberlegacy(A,B,logical(flaginds(1)));

        else

            [lia,locb] = ismemberlegacy(A,B,logical(flaginds(1)));

        end

    else % 'R2012a' (default behavior)

        if nargout < 2

            lia = ismemberR2012a(A,B,logical(flaginds(1)));

        else

            [lia,locb] = ismemberR2012a(A,B,logical(flaginds(1)));

        end

    end

end 

end