dlib C++ Library - example_mex_callback.cpp

// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
#include "call_matlab.h"
#include "dlib/matrix.h"
using namespace dlib;
using namespace std;
/*
 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.
*/
void mex_function (
 const matrix<double>& A,
 const function_handle& f,
 matrix<double>& result
) 
{
 // The f argument to this function is a function handle passed from MATLAB. To
 // call it we use the following syntax:
 call_matlab(f, A, returns(result));
 // This is equivalent to result = f(A). Therefore, the returns(variable) syntax 
 // is used to indicate which variables are outputs of the function.
 // Another thing we can do is call MATLAB functions based on their string name
 // rather than a function_handle. Here is an example of calling eigs(). 
 matrix<double> m(2,2);
 m = 1,2,
 3,4;
 matrix<double> v,d;
 // This is equivalent to [v,d] = eigs(m);
 call_matlab("eigs", m, returns(v), returns(d));
 cout << "eigenvectors: \n" << v << endl;
 cout << "eigenvalues: \n" << d << endl;
}
// #including this brings in all the mex boiler plate needed by MATLAB.
#include "mex_wrapper.cpp"