Building a Matlab Engine application with Qt Framework

Hello,

I have submitted this question in the Qt Forum as well ( Qt Forums ).

I am having problems compiling Matlab Engine libraries with a small qt application. I have tried using Matlab 2016b, 2017a and 2017b. I am using Ubuntu 16.04, gcc 5.4.0 (and gcc 4.9) and Qt 5.10.0.

The example I am providing is using Matlab 2017a, but I have the same issue when I use 2017b and 2016b. The application I am trying to compile is the following

 #include <QcoreApplication>
 #include <QDebug>
 #include "engine.h"
 #include "matrix.h"

 int main(int argc, char *argv[])
 {
    Engine* m_engine;

    m_engine = engOpen("");

    if (!(m_engine = engOpen(""))) {
        qDebug()<<"\nCan't start MATLAB engine\n";
        exit(-1);
    }
 }

My Qmake .pro file is :

 MATLAB_ROOT_PATH = /usr/local/MATLAB/R2017a

 MATLAB_INCLUDE_PATH = $${MATLAB_ROOT_PATH}/extern/include
 MATLAB_LIB_PATH     = $${MATLAB_ROOT_PATH}/bin/glnxa64
 MATLAB_SYS_DIR = $${MATLAB_ROOT_PATH}/sys/os/glnxa64

 LIBS += -L$${MATLAB_LIB_PATH} -lmx -lmex -lmat -lm -leng
 LIBS += -L$${MATLAB_SYS_DIR} -lstdc++

 INCLUDEPATH += $$MATLAB_INCLUDE_PATH
 DEPENDPATH  += $$MATLAB_INCLUDE_PATH

 QMAKE_RPATHDIR += $$MATLAB_LIB_PATH
 QMAKE_RPATHDIR += $$MATLAB_SYS_DIR

 DEFINES += QT_DEPRECATED_WARNINGS
 SOURCES += main.cpp

Compiling the code above results in the following runtime error :

 ./matlab_test: /usr/local/MATLAB/R2017a/bin/glnxa64/libQt5Core.so.5: no version information available (required by ./matlab_test)
 ./matlab_test: /usr/local/MATLAB/R2017a/bin/glnxa64/libQt5Core.so.5: no version information available (required by ./matlab_test)
 ./matlab_test: relocation error: ./matlab_test: symbol qt_version_tag, version Qt_5.10 not defined in file libQt5Core.so.5 with link time reference

I have seen in the documentation that gcc 4.9 is only supported, but I get the same error. I have tried changing the libraries I link and the result is again the same. In order to solve the above error I add the Qt library directory to the QMAKE_RPATHDIR

 QMAKE_RPATHDIR += $$QT_LIB_DIR \

which then results in the following compilation error

 /usr/local/MATLAB/R2017b/bin/glnxa64/libmwi18n.so: undefined reference to `icu_56::UnicodeString::UnicodeString(char16_t const*, int)'
 /usr/local/MATLAB/R2017b/bin/glnxa64/libmwi18n.so: undefined reference to `UCNV_FROM_U_CALLBACK_ESCAPE_WITH_INVISIBLE_CHARS_56'
 /usr/local/MATLAB/R2017b/bin/glnxa64/libmwi18n.so: undefined reference to `UCNV_FROM_U_CALLBACK_STOP_WITH_INVISIBLE_CHARS_56'
 /usr/local/MATLAB/R2017b/bin/glnxa64/libmwi18n.so: undefined reference to `icu_56::UnicodeString::UnicodeString(char16_t const*)'
 /usr/local/MATLAB/R2017b/bin/glnxa64/libmwi18n.so: undefined reference to `icu_56::UnicodeString::doCompare(int, int, char16_t const*, int, int) const'

I have seen there is an issue with the stdc++ library that is included with the Matlab installation, which after replacing I still get the error above relating to the libmwi18n.so.

Finally I have tried using the MatlabEngine.so which are included only with Matlab 2017b. Using this library and linking with the libstdc++ of the compiler, I am able to compile, but I get the runtime error :

 /usr/local/MATLAB/R2017b/bin/glnxa64/libicuio.so.56: undefined symbol: _ZN6icu_5613UnicodeString8doAppendEPKDsii

I am not sure if it is a compiler issue, since I am using both g++-4.9 and the one provided with Ubuntu 16.04.

[Vincent Hui]

Hi,

I have tried using the MatlabEngine.so with Qt 5.10.1 too. The same runtime error I got:

/opt/MATLAB/R2017b/bin/glnxa64/libicuio.so.56: undefined symbol: _ZN6icu_5613UnicodeString8doAppendEPKDsii

How to slove the problem?

Thanks

[Walter Roberson]

That name demangles to

icu_56::UnicodeString::doAppend(char16_t const*, int, int)

Answer 1

[Walter Roberson]

See https://stackoverflow.com/questions/35246695/undefined-reference-to-icu-56unicodestringunicodestringsigned-char-unsign