function y = mean(x,dim,flag)

%MEAN   Average or mean value.

%   S = MEAN(X) is the mean value of the elements in X

%   if X is a vector. For matrices, S is a row

%   vector containing the mean value of each column.

%   For N-D arrays, S is the mean value of the

%   elements along the first array dimension whose size

%   does not equal 1.

%   If X is floating point, that is double or single,

%   S has the same class as X. If X is of integer

%   class, S has class double.

%

%   MEAN(X,DIM) takes the mean along the dimension DIM

%   of X.

%

%   S = MEAN(X,'double') and S = MEAN(X,DIM,'double')

%   returns S in double, even if X is single.

%

%   S = MEAN(X,'native') and S = MEAN(X,DIM,'native')

%   returns S in the same class as X.

%

%   S = MEAN(X,'default') and S = MEAN(X,DIM,'default')

%   are equivalent to S = MEAN(X) and S = MEAN(X,DIM)

%   respectively.

%

%   Example: If X = [1 2 3; 3 3 6; 4 6 8; 4 7 7];

%

%   then mean(X,1) is [3.0000 4.5000 6.0000] and

%   mean(X,2) is [2.0000 4.0000 6.0000 6.0000].'

%

%   Class support for input X:

%      float: double, single

%      integer: uint8, int8, uint16, int16, uint32,

%               int32, uint64, int64

%

%   See also MEDIAN, STD, MIN, MAX, VAR, COV, MODE.

%   Copyright 1984-2013 The MathWorks, Inc.

if nargin==2 && ischar(dim) 

    flag = dim;

elseif nargin < 3 

    flag = 'default'; 

end 

if nargin == 1 || (nargin == 2 && ischar(dim)) 

    % preserve backward compatibility with 0x0 empty

    if isequal(x,[]) 

        y = sum(x,flag)/0;

        return

    end

    dim = find(size(x)~=1,1); 

    if isempty(dim), dim = 1; end 

end 

if ~isobject(x) && isinteger(x)  

    isnative = strcmp(flag,'native');

    if intmin(class(x)) == 0  % unsigned integers

        y = sum(x,dim,flag);

        if (isnative && all(y(:) < intmax(class(x)))) || ...

                (~isnative && all(y(:) <= flintmax))

            % no precision lost, can use the sum result

            y = y/size(x,dim);

        else  % throw away and recompute

            y = intmean(x,dim,flag);

        end

    else  % signed integers

        ypos = sum(max(x,0),dim,flag);

        yneg = sum(min(x,0),dim,flag);

        if (isnative && all(ypos(:) < intmax(class(x))) && ...

                all(yneg(:) > intmin(class(x)))) || ...

                (~isnative && all(ypos(:) <= flintmax) && ...

                all(yneg(:) >= -flintmax))

            % no precision lost, can use the sum result

            y = (ypos+yneg)/size(x,dim);

        else  % throw away and recompute

            y = intmean(x,dim,flag);    

        end

    end

else 

    y = sum(x,dim,flag)/size(x,dim); 

end 

end