% Delivered to the Government in Accordance with Contract FA8650-10-C-7080
% 
%  (c) 2011 United Technologies Corp.
% Developed with the sponsorship of the Defense Advanced Research Projects Agency (DARPA).
%  
% Permission is hereby granted, free of charge, to any person obtaining a copy of this data, including any software or models in source or binary form, as well as any drawings, specifications, and documentation (collectively "the Data"), to deal in the Data without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Data, and to permit persons to whom the Data is furnished to do so, subject to the following conditions:
%  
% The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Data.
%  
% THE DATA IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS, SPONSORS, DEVELOPERS, CONTRIBUTORS, OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE DATA OR THE USE OR OTHER DEALINGS IN THE DATA.
% 


function A = allcomb(varargin)
% ALLCOMB - All combinations
%    B = ALLCOMB(A1,A2,A3,...,AN) returns all combinations of the elements
%    in A1, A2, ..., and AN. B is P-by-N matrix is which P is the product
%    of the number of elements of the N inputs.
%    Empty inputs yields an empty matrix B of size 0-by-N. Note that
%    previous versions (1.x) simply ignored empty inputs.
%
%    Example:
%       allcomb([1 3 5],[-3 8],[0 1]) ;
%         1  -3   0
%         1  -3   1
%         1   8   0
%         ...
%         5  -3   1
%         5   8   0
%         5   8   1
%
%    ALLCOMB(A1,..AN,'matlab') causes the first column to change fastest.
%    This is more consistent with matlab indexing. Example:
%    allcomb(1:2,3:4,5:6,'matlab') %->
%      1   3   5
%      2   3   5
%      1   4   5
%      ...
%      2   4   6
%
%    This functionality is also known as the cartesian product.
%
%    See also NCHOOSEK, PERMS,
%    and COMBN (Matlab Central FEX)

% for Matlab R13+
% version 2.1 (feb 2011)
% (c) Jos van der Geest
% email: jos@jasen.nl

% History
% 1.1 (feb 2006), removed minor bug when entering empty cell arrays;
%     added option to let the first input run fastest (suggestion by JD)
% 1.2 (jan 2010), using ii as an index on the left-hand for the multiple
%     output by NDGRID. Thanks to Jan Simon, for showing this little trick
% 2.0 (dec 2010). Bruno Luong convinced me that an empty input should
% return an empty output.
% 2.1 (feb 2011). A cell as input argument caused the check on the last
%      argument (specifying the order) to crash.

error(nargchk(1,Inf,nargin)) ;

% check for empty inputs
q = ~cellfun('isempty',varargin) ;
if any(~q),
    warning('ALLCOMB:EmptyInput','Empty inputs result in an empty output.') ;
    A = zeros(0,nargin) ;
else
    
    ni = sum(q) ;
    
    argn = varargin{end} ;
    %ischar(argn) 
    if ischar(argn) && (strcmpi(argn,'matlab') || strcmpi(argn,'john')),
        % based on a suggestion by JD on the FEX
        ni = ni-1 ;
        ii = 1:ni ;
        q(end) = 0 ;
    else
        % enter arguments backwards, so last one (AN) is changing fastest
        ii = ni:-1:1 ;
    end
    
    if ni==0,
        A = [] ;
    else
        args = varargin(q) ;
        if ~all(cellfun('isclass',args,'double')),
            error('All arguments should be arrays of doubles') ;
        end
        if ni==1,
            A = args{1}(:) ;
        else
            % flip using ii if last column is changing fastest
            [A{ii}] = ndgrid(args{ii}) ;
            % concatenate
            A = reshape(cat(ni+1,A{:}),[],ni) ;
        end
    end
end
