% compile the mex file
mex mexme.cpp

input = [ 1 2 3 10; ...
          4 5 6 12; ...
          7 8 9 11];

% run the mex file
[output1, output2] = mexme(input);

output1
output2

% after reading 'mexme.cpp' try changing it, 
% so that it returns one more matrix of size 1x1,
% which contains the average of the values of 
% the input matrix