Undefine symbols for architecture x86_64 using FFTW

Question

Ceeloss-MacBook-Pro:desktop ceelos$ gcc -o prog -I/usr/local/include test.c
Undefined symbols for architecture x86_64:
  "_fftw_destroy_plan", referenced from:
      _main in test-IBqBdS.o
  "_fftw_execute", referenced from:
      _main in test-IBqBdS.o
  "_fftw_plan_dft_1d", referenced from:
      _main in test-IBqBdS.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Ceeloss-MacBook-Pro:desktop ceelos$ 

What's this telling me?

Honan

Answer 1

It's telling you that you forgot to use -L and -l to tell gcc where the FFTW libraries are and what they're called.

Dias

sorry, I'm really new to this. How exactly would I specify this? My library is under /usr/local/lib – Honan

-L takes the library location, and -l takes the library filename minus the "lib" and the extension. -L/usr/local/lib -lfftwwhatever – Dias

hmm, I keep getting "ld: library not found for -libfftw3.la clang: error: linker command failed with exit code 1 (use -v to see invocation)" strange, i'm staring at the file there right now. – Honan

Please read my comment again. I believe that you have missed a couple of things. – Dias

Sorry for having a hard time with this. I entered "gcc -o prog -I/usr/local/include test.c -L/usr/local/lib -lfftw3f.la" and it gave me this error. – Honan

Try -lfftw3f instead. But you may need to reorder the options. – Dias

Yeah, I tried that and reordering, still doesn't find the library. Weird. – Honan

What is the .dylib file called? – Dias

I don't have one. the make install didn't create one nor did it come with the zip file. Unless I was supposed to create one myself. – Honan

yes, two, a regular one and one for floats. libfftw3.a and libfftw3f.a – Honan

That's really strange. If you're passing both arguments and it still can't find the library then I don't know what's going on. – Dias

It's fine, I'll see what I figure. Thanks for all your help. I appreciate it. – Honan

Hey, I was able to add the .dylibs. – Honan