Could not find matlabEngine using the following names: libMatlabEngine

Hi,

I am currently trying to run some MATLAB code in a c++ project. Obviously, to make things more complicated I am also new to both c++ and cmake.

So here is my top-Level CMakelists.txt:

cmake_minimum_required(VERSION 3.19)
project(matlabapi)
set(CMAKE_CXX_STANDARD 14)

# sets the matlab root directory
set(Matlab_ROOT_DIR  /usr/local/MATLAB/R2021a)

# included directories
include_directories(${Matlab_ROOT_DIR}/extern/bin/glnxa64/)
    # print all included directories
    get_property(dirs DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY INCLUDE_DIRECTORIES)
    foreach(dir ${dirs})
        message(STATUS "Included Directory is: '${dir}'")
    endforeach()

# Libraries
find_library(matlabEngine libMatlabEngine REQUIRED)

# Executable
add_executable(matlabapi main.cpp)

# Linker stuff
target_link_libraries(matlabapi matlabEngine)

and the main.cpp which is the executable:

#include <iostream>
#include "MatlabEngine.hpp"
#include "MatlabDataArray.hpp"

int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}

From my understanding, Cmake should find the library here:

/usr/local/MATLAB/R2021a/extern/bin/glnxa64/

which includes two files:

libMatlabDataArray.so  libMatlabEngine.so

What am I missing? Cmake throws the error in cmake configuration time:

CMake Error at CMakeLists.txt:17 (find_library):
  Could not find matlabEngine using the following names: libMatlabEngine

Answer 1

[Kojiro Saito]

According to this document, we can know which compile options to be passed to g++.

g++ -std=c++11 -I <matlabroot>/extern/include/ -L <matlabroot>/extern/bin/glnxa64/ -pthread myEngineApp.cpp -lMatlabDataArray -lMatlabEngine

And when executing the MATLAB Engine API for C++, we need to add LD_LIBRARY_PATH.

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:matlabroot/extern/bin/glnxa64:matlabroot/sys/os/glnxa64

With that, CMakeLists.txt would be the following.

cmake_minimum_required(VERSION 3.19)
project(matlabapi)

# As of R2021a, C++ version ~11 and 14 are supported
set(CMAKE_CXX_STANDARD 14)

# To avoid "undefined reference to symbol 'pthread_create@@GLIBC_x.x.x" error
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread") 

# Set the matlab root directory
set(Matlab_ROOT_DIR  /usr/local/MATLAB/R2021a)

# Set LD_LIBRARY_PATH for execution
set(LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:${Matlab_ROOT_DIR}/extern/bin/glnxa65:${Matlab_ROOT_DIR}/sys/os/glnxa64)

# Included directories
include_directories(${Matlab_ROOT_DIR}/extern/include/)

# Print all included directories
get_property(dirs DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY INCLUDE_DIRECTORIES)
foreach(dir ${dirs})
        message(STATUS "Included Directory is: '${dir}'")
endforeach()

# Add linker search directories
link_directories(${Matlab_ROOT_DIR}/extern/bin/glnxa64)

# Executable
add_executable(matlabapi main.cpp)

# Linker stuff
# Linker to libMatlabDataArray in link_directories
target_link_libraries(matlabapi MatlabDataArray)
# Linker to libMatlabEngine in link_directories
target_link_libraries(matlabapi MatlabEngine)

Next, create a build directory and do cmake.

mkdir build
cd build
cmake ..

You will get CMakeCache.txt, CMakeFiles, cmake_install.cmake and Makefile. Build this file.

make

You will get matlabapi execution file. Then, run

./matlabapi