# dlib C++ Library - example_mex_function.cpp

    // The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt

    #include "dlib/matrix.h"
    using namespace dlib;
    using namespace std;

    /*!
        This file defines a function callable from MATLAB once you mex it.

        It computes the same thing as the following MATLAB function:

            function [A, B] = example_mex_function(x, y, some_number)
                A = x+y;
                B = sum(sum(x+y));
                disp(['some_number: ' num2str(some_number)])
            end

        VALID INPUT AND OUTPUT ARGUMENTS
            The mex wrapper can handle the following kinds of input and output arguments:
                - Types corresponding to a MATLAB matrix
                    - a dlib::matrix containing any kind of scalar value.
                    - a dlib::array2d containing any kind of scalar value.
                    - a dlib::vector containing any kind of scalar value.
                    - a dlib::point
                    - matrix_colmajor or fmatrix_colmajor
                      These are just typedefs for matrix containing double or float and using a
                      column major memory layout.  However, they have the special distinction
                      of being fast to use in mex files since they sit directly on top of
                      MATLAB's built in matrices.  That is, while other types of arguments copy
                      a MATLAB object into themselves, the matrix_colmajor and fmatrix_colmajor
                      do no such copy and are effectively zero overhead methods for working on
                      MATLAB's matrices.

                - RGB color images
                    - dlib::array2d<dlib::rgb_pixel> can be used to represent
                      MATLAB uint8 MxNx3 images.

                - Types corresponding to a MATLAB scalar
                    - any kind of scalar value, e.g. double, int, etc.

                - Types corresponding to a MATLAB string
                    - std::string

                - Types corresponding to a MATLAB cell array
                    - a std::vector or dlib::array containing any of the above
                      types of objects or std::vector or dlib::array objects.

                - matlab_struct and matlab_object.  These are special types defined in the
                  call_matlab.h file and correspond to matlab structs and arbitrary matlab
                  objects respectively.
    !*/

    // You can also define default values for your input arguments.  So
    // here we say that if the user in MATLAB doesn't provide the "some_number"
    // then it will get a value of 3.141.
    #define ARG_5_DEFAULT 3.141

    // Make a function named mex_function() and put your code inside it.
    // Note that the return type should be void.  Use non-const reference
    // arguments to return outputs.  Finally, mex_function() must have no
    // more than 20 arguments.
    void mex_function (
        const matrix_colmajor& x,
        const matrix_colmajor& y,
        matrix_colmajor& out1,
        double& out2,
        double some_number
    )
    {
        out1 = x + y;
        out2 = sum(x+y);

        // we can also use cout to print things as usual:
        cout << "some_number: "<< some_number << endl;
    }

    // #including this brings in all the mex boiler plate needed by MATLAB.
    #include "mex_wrapper.cpp"