cannot find -lfftw2xc_single_gnu

[bruce_spc]

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

[VidyalathaB_Intel]

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.

[bruce_spc]

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.

[VidyalathaB_Intel]

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.

[VidyalathaB_Intel]

Hi Bruce,

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

Regards,

Vidya.

[VidyalathaB_Intel]

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.