call Matlab from C++ on Ubuntu

Question

I'm trying to call Matlab function from C++ (for NS-3) in Eclipse IDE on Ubuntu 18.04. I used Matlab Library Compiler to compile the .m file into a C++ Shared Library. How do I call the function correctly?

The corresponding MATLAB Runtime has been installed and configured. At first it can't find "mclmcrrt.h", I copied the /usr/local/MATLAB/R2018b/extern/include folder and changed the library header to include "./include/mclmcrrt.h". Then the IDE can find the header files correctly.

A C++ script to test the library as follows:

/* C = A+B */
#include <iostream>
#include "libtestAdd.h"

using namespace std;

int main(){
    double A[] = {1};
    double B[] = {2};
    int nargout = 1;

    mwArray input_A (1,1,mxDOUBLE_CLASS,mxREAL);
    input_A.SetData(M,1);
    mwArray input_B (1,1,mxDOUBLE_CLASS,mxREAL);
    input_B.SetData(K,1);
    mwArray C (1,1,mxDOUBLE_CLASS,mxREAL);

    if (!mclInitializeApplication(NULL,0)){
        std::cerr << "Could not initialize the application properly."
                  << std::endl;
        return -1;
    }
    libtestAddInitialize();
    testAdd(nargout, C, input_A, input_B);
    libtestAddTerminate();

    return 1;
}

The Matlab function is C=A+B.

The .m file has been compiled into a C++ Shared Library ("libtestAdd.so" and "libtestAdd.h"). The C++ script try to call the "testAdd" function from the library.

Matlab Runtime has been correctly installed. /etc/profile has been changed to export the follows path to LD_LIBRARY_PATH environment variable:

/usr/local/MATLAB/MATLAB_Runtime/v95/runtime/glnxa64:/usr/local/MATLAB/MATLAB_Runtime/v95/bin/glnxa64:/usr/local/MATLAB/MATLAB_Runtime/v95/sys/os/glnxa64

The error messages as follows:

~/Desktop/libtestAdd/for_testing$ cd "/home/csrl/Desktop/libtestAdd/for_testing/" && g++ main.cpp -o main && "/home/csrl/Desktop/libtestAdd/for_testing/"main
/tmp/ccyFn7iq.o: In function `main':
main.cpp:(.text+0xde): undefined reference to `libtestAddInitialize'
main.cpp:(.text+0xf4): undefined reference to `testAdd(int, mwArray&, mwArray const&, mwArray const&)'
main.cpp:(.text+0xf9): undefined reference to `libtestAddTerminate'
/tmp/ccyFn7iq.o: In function `mwException::mwException()':
main.cpp:(.text._ZN11mwExceptionC2Ev[_ZN11mwExceptionC5Ev]+0x46): undefined reference to `mclcppCreateError_proxy'
/tmp/ccyFn7iq.o: In function `mwException::mwException(char const*)':
main.cpp:(.text._ZN11mwExceptionC2EPKc[_ZN11mwExceptionC5EPKc]+0x5a): undefined reference to `mclcppCreateError_proxy'
/tmp/ccyFn7iq.o: In function `mwException::mwException(error_info*, bool)':
main.cpp:(.text._ZN11mwExceptionC2EP10error_infob[_ZN11mwExceptionC5EP10error_infob]+0x61): undefined reference to `ref_count_obj_addref_proxy'
main.cpp:(.text._ZN11mwExceptionC2EP10error_infob[_ZN11mwExceptionC5EP10error_infob]+0x7a): undefined reference to `mclcppCreateError_proxy'
/tmp/ccyFn7iq.o: In function `mwException::~mwException()':
main.cpp:(.text._ZN11mwExceptionD2Ev[_ZN11mwExceptionD5Ev]+0x36): undefined reference to `ref_count_obj_release_proxy'
/tmp/ccyFn7iq.o: In function `mwException::what() const':
main.cpp:(.text._ZNK11mwException4whatEv[_ZNK11mwException4whatEv]+0x25): undefined reference to `error_info_get_message_proxy'
/tmp/ccyFn7iq.o: In function `mwException::raise_error()':
main.cpp:(.text._ZN11mwException11raise_errorEv[_ZN11mwException11raise_errorEv]+0x2a): undefined reference to `mclcppGetLastError_proxy'
/tmp/ccyFn7iq.o: In function `mwArray::mwArray(unsigned long, unsigned long, mxClassID, mxComplexity)':
main.cpp:(.text._ZN7mwArrayC2Emm9mxClassID12mxComplexity[_ZN7mwArrayC5Emm9mxClassID12mxComplexity]+0x52): undefined reference to `mclGetMatrix_proxy'
/tmp/ccyFn7iq.o: In function `mwArray::~mwArray()':
main.cpp:(.text._ZN7mwArrayD2Ev[_ZN7mwArrayD5Ev]+0x26): undefined reference to `ref_count_obj_release_proxy'
/tmp/ccyFn7iq.o: In function `mwArray::SetData(double*, unsigned long)':
main.cpp:(.text._ZN7mwArray7SetDataEPdm[_ZN7mwArray7SetDataEPdm]+0x2b): undefined reference to `array_ref_set_numeric_mxDouble_proxy'
collect2: error: ld returned 1 exit status

Answer 1

You need to link with the .so file. Add it to the end of your compile command.