Test Your Build Environment

To test your installation and environment, save the following C++ code in a file named testFeval.cpp (you can use any name). To build the engine application, use these commands from your command window:

mex -setup -client engine C++

Select the installed compiler you want to use when prompted by the mex setup script. Then call the mex command to build your program. Ensure that the MATLAB^® Engine API for C++ supports the compiler you select. For an up-to-date list of supported compilers, see the Supported and Compatible Compilers website.

mex -v -client engine testFeval.cpp

The mex command saves the executable file in the same folder.

#include "MatlabDataArray.hpp"
#include "MatlabEngine.hpp"
#include <iostream>
void callSQRT() {

    using namespace matlab::engine;

    // Start MATLAB engine synchronously
    std::unique_ptr<MATLABEngine> matlabPtr = startMATLAB();

    //Create MATLAB data array factory
    matlab::data::ArrayFactory factory;

    // Define a four-element typed array
    matlab::data::TypedArray<double> const argArray = 
        factory.createArray({ 1,4 }, { -2.0, 2.0, 6.0, 8.0 });

    // Call MATLAB sqrt function on the data array
    matlab::data::Array const results = matlabPtr->feval(u"sqrt", argArray);

    // Display results
    for (int i = 0; i < results.getNumberOfElements(); i++) {
        double a = argArray[i];
        std::complex<double> v = results[i];
        double realPart = v.real();
        double imgPart = v.imag();
        std::cout << "Square root of " << a << " is " << 
            realPart << " + " << imgPart << "i" << std::endl;
    }
}

int main() {
    callSQRT();
    return 0;
}

Here is the output from this program. In this case, MATLAB returns a complex array because one of the numbers in the data array is negative.

Square root of -2 is 0 + 1.41421i
Square root of 2 is 1.41421 + 0i
Square root of 6 is 2.44949 + 0i
Square root of 8 is 2.82843 + 0i