I'm sorry, but it is not possible to directly use MATLAB functions in C++. However, you can create a MATLAB engine application in C++ that allows you to call MATLAB functions from within your C++ code.

To create a MATLAB engine application in C++, you will need to follow these general steps:

1. Install the MATLAB engine API for C++. This can be done by installing the MATLAB software and selecting the "MATLAB Engine API for C++" option during the installation process.

2. Include the necessary header files in your C++ code to use the MATLAB engine API. These header files can be found in the MATLAB installation directory.

3. Initialize the MATLAB engine in your C++ code by creating an instance of the Engine class.

4. Call MATLAB functions from your C++ code using the engEvalString function. This function takes a string containing the MATLAB code you want to execute and returns the output of that code as a string.

5. Shut down the MATLAB engine when you are finished by calling the Engine::Close function.

Here is an example of how to call a MATLAB function from C++ using the MATLAB engine API: 

#include "mat.h"
#include "engine.h"

int main()
{
    // Initialize the MATLAB engine
    Engine* eng = engOpen(NULL);

    // Call a MATLAB function
    engEvalString(eng, "a = rand(3);");
    engEvalString(eng, "b = sum(a);");
    mxArray* b = engGetVariable(eng, "b");
    double* b_data = mxGetPr(b);

    // Display the result
    for (int i = 0; i < mxGetN(b); i++)
    {
        std::cout << "b[" << i << "] = " << b_data[i] << std::endl;
    }

    // Clean up
    mxDestroyArray(b);
    engClose(eng);

    return 0;
}

In this example, we initialize the MATLAB engine by creating an instance of the Engine class. We then call the MATLAB functions rand and sum using the engEvalString function. We retrieve the result of the sum function using the engGetVariable function, and then extract the data from the returned mxArray. Finally, we display the result and clean up by destroying the mxArray and closing the MATLAB engine.