topic Re:cannot find -lfftw2xc_single_gnu in Intel® oneAPI Math Kernel Library

cannot find -lfftw2xc_single_gnu

bruce_spc — Fri, 23 Dec 2022 00:29:17 GMT

Getting a linker error trying to find the fftw2x library. I have pre-built the library using the makefile in $MKL_ROOT/interfaces

make libintel64 compiler=gnu PRECISION=MKL_SINGLE INSTALL_DIR=../../lib/intel64/

I can see the .a file in a listing with all the other MKL library files:

-rwxrwxrwx 1 root root 120102 Dec 22 13:38 libfftw2xc_single_gnu.a* -rwxrwxrwx 1 root root 83014 Dec 22 13:38 libfftw2xc_single_intel.a*

I am then using cmake to build my program. Within CMakeLists.txt

find_package(MKL CONFIG REQUIRED) set(MKL_LIBS fftw2xc_single_gnu) target_link_libraries(app PUBLIC ${MKL_LIBS})

The output of cmake includes these:

-- MKL_ARCH: None, set to ` intel64` by default -- MKL_ROOT /opt/intel/oneapi/mkl/2022.1.0 -- MKL_LINK: static -- MKL_INTERFACE_FULL: None, set to ` intel_ilp64` by default -- MKL_THREADING: None, set to ` intel_thread` by default -- MKL_MPI: None, set to ` intelmpi` by default -- Found MKL: intelmpi -- Found MKL: /opt/intel/oneapi/mkl/2022.1.0 -- Found MKL: /usr/lib/x86_64-linux-gnu/libmkl_intel_ilp64.a -- Found MKL: /usr/lib/x86_64-linux-gnu/libmkl_core.a -- Found MKL: /usr/lib/x86_64-linux-gnu/libmkl_intel_thread.a -- Found MKL: /opt/intel/oneapi/compiler/latest/linux/compiler/lib/intel64/libiomp5.so

cmake also creates a link.txt file with the following as part of the linker command line:

/usr/bin/c++ <bunch of other stuff> -lfftw2xc_single_gnu -lmkl_intel_ilp64 -lmkl_intel_thread -lmkl_core

However when I try to make the target it compiles fine but fails to link:

/usr/bin/ld: cannot find -lfftw2xc_single_gnu collect2: error: ld returned 1 exit status

Re:cannot find -lfftw2xc_single_gnu

VidyalathaB_Intel — Fri, 23 Dec 2022 16:35:45 GMT

Hi Bruce,

Thanks for reaching out to us.

Could you please provide us with a sample reproducer to reproduce the error that you are getting to have a quick check from our end?

Regards,

Vidya.

Re: cannot find -lfftw2xc_single_gnu

bruce_spc — Fri, 23 Dec 2022 16:56:39 GMT

Our source code is too complicated to share easily (multiple repositories as submodules, multiple levels of cmake, etc). It will take me some time to try to make a simplified example that exhibits this problem.

Can you just answer these two simple questions?

1) How do you link the FFTW2XC library? As I mentioned above I built the library using the makefile in

/opt/intel/oneapi/mkl/2022.1.0/interfaces/fftw2xc

and I installed it in the same directory as all the other MKL libraries are found.

2) I am still getting a link error

undefined reference to 'vcCISI'

on linux when I had no such error on Windows compiling under Visual Studio.

Re:cannot find -lfftw2xc_single_gnu

VidyalathaB_Intel — Wed, 28 Dec 2022 16:45:33 GMT

Hi Bruce,

Could you please confirm if you were able to locate the libfftw2xc_single_gnu.a file in your system?

Also, try checking with the sample CMakeLists.txt file provided here https://www.intel.com/content/www/us/en/develop/documentation/onemkl-linux-developer-guide/top/getting-started/cmake-config-for-onemkl.html

Regarding the 2nd issue

Is it possible to provide us with the sample reproducer to reproduce the undefined reference to 'vcCISI' error that you are getting?

Regards,

Vidya.

Re:cannot find -lfftw2xc_single_gnu

VidyalathaB_Intel — Wed, 04 Jan 2023 12:34:22 GMT

Hi Bruce,

As we haven't heard back from you, could you please provide us with an update regarding the issue?

Regards,

Vidya.

Re:cannot find -lfftw2xc_single_gnu

VidyalathaB_Intel — Wed, 11 Jan 2023 15:54:34 GMT

Hi Bruce,

As we haven't heard back from you, we are closing this thread. Please post a new question if you need any additional assistance from Intel as this thread will longer be monitored.

Regards,

Vidya.