How to link LAPACKE to a c++ project using cmake?

Question

I have installed liblapacke-dev and liblapack-dev, and use find_package(LAPACK) and target_link_libraries(XXX PUBLIC LAPACK::LAPACK) to find and link them. However, the compiler complains that it cannot find LAPACKE_xxx during the linking process.

Here is a minimum working example:

// main.cc
#include "lapacke.h"

int main() {
    LAPACKE_dgbsv(LAPACK_ROW_MAJOR,
        1, 1, 1, 1, nullptr, 1, nullptr, nullptr, 1
    );
}

#CMakeLists.txt
cmake_minimum_required(VERSION 3.22)
project(test)

set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

find_package(LAPACK REQUIRED)
add_executable(main main.cc)
target_link_libraries(main LAPACK::LAPACK)

It seems that I need to find LAPACKE instead of LAPACK, but the problem is that I did not see any lapacke-config.cmake installed. How can I tell the compiler to find and link it?

Answer 1

You will need to add to your target_link_libraries the -llapacke option, like this: target_link_libraries(main LAPACK::LAPACK -llapacke)

Otherwise, if you want to be fancier you can use the FindLAPACKE.cmake file that these people created: https://github.com/isl-org/Open3D/blob/master/3rdparty/cmake/FindLAPACKE.cmake

You will need to have a cmake/ directory within our build directory and append it to your CMAKE_MODULE_PATH like this:

set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH})

Then you can use: find_package(LAPACKE REQUIRED) and instead of using -llapacke in your target_link_libraries you can use lapacke