<html><!-- Created using the cpp_pretty_printer from the dlib C++ library.  See http://dlib.net for updates. --><head><title>dlib C++ Library - example_mex_callback.cpp</title></head><body bgcolor='white'><pre>
<font color='#009900'>// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
</font>
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='call_matlab.h.html'>call_matlab.h</a>"
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='dlib/matrix.h.html'>dlib/matrix.h</a>"

<font color='#0000FF'>using</font> <font color='#0000FF'>namespace</font> dlib;
<font color='#0000FF'>using</font> <font color='#0000FF'>namespace</font> std;

<font color='#009900'>/*
    This mex function takes a MATLAB function handle, calls it, and
    returns the results.

    For example, you can call this function in MATLAB like so:
        A = magic(3)
        y = example_mex_callback(A, @(x)x+x)

    This will result in y containing the value 2*A.
*/</font>

<font color='#0000FF'><u>void</u></font> <b><a name='mex_function'></a>mex_function</b> <font face='Lucida Console'>(</font>
    <font color='#0000FF'>const</font> matrix<font color='#5555FF'>&lt;</font><font color='#0000FF'><u>double</u></font><font color='#5555FF'>&gt;</font><font color='#5555FF'>&amp;</font> A,
    <font color='#0000FF'>const</font> function_handle<font color='#5555FF'>&amp;</font> f,
    matrix<font color='#5555FF'>&lt;</font><font color='#0000FF'><u>double</u></font><font color='#5555FF'>&gt;</font><font color='#5555FF'>&amp;</font> result
<font face='Lucida Console'>)</font> 
<b>{</b>
    <font color='#009900'>// The f argument to this function is a function handle passed from MATLAB.  To
</font>    <font color='#009900'>// call it we use the following syntax:
</font>    <font color='#BB00BB'>call_matlab</font><font face='Lucida Console'>(</font>f, A, <font color='#BB00BB'>returns</font><font face='Lucida Console'>(</font>result<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>;
    <font color='#009900'>// This is equivalent to result = f(A). Therefore, the returns(variable) syntax 
</font>    <font color='#009900'>// is used to indicate which variables are outputs of the function.
</font>



    <font color='#009900'>// Another thing we can do is call MATLAB functions based on their string name
</font>    <font color='#009900'>// rather than a function_handle.  Here is an example of calling eigs().   
</font>    matrix<font color='#5555FF'>&lt;</font><font color='#0000FF'><u>double</u></font><font color='#5555FF'>&gt;</font> <font color='#BB00BB'>m</font><font face='Lucida Console'>(</font><font color='#979000'>2</font>,<font color='#979000'>2</font><font face='Lucida Console'>)</font>;
    m <font color='#5555FF'>=</font> <font color='#979000'>1</font>,<font color='#979000'>2</font>,
        <font color='#979000'>3</font>,<font color='#979000'>4</font>;
    matrix<font color='#5555FF'>&lt;</font><font color='#0000FF'><u>double</u></font><font color='#5555FF'>&gt;</font> v,d;

    <font color='#009900'>// This is equivalent to [v,d] = eigs(m);
</font>    <font color='#BB00BB'>call_matlab</font><font face='Lucida Console'>(</font>"<font color='#CC0000'>eigs</font>", m, <font color='#BB00BB'>returns</font><font face='Lucida Console'>(</font>v<font face='Lucida Console'>)</font>, <font color='#BB00BB'>returns</font><font face='Lucida Console'>(</font>d<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>;
    cout <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>eigenvectors: \n</font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> v <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> endl;
    cout <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>eigenvalues:  \n</font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> d <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> endl;
<b>}</b>



<font color='#009900'>// #including this brings in all the mex boiler plate needed by MATLAB.
</font><font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='mex_wrapper.cpp.html'>mex_wrapper.cpp</a>"


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