Installing OpenMP on Mac OS X 10.11

Question

How can I get OpenMP to run on Mac OSX 10.11, so that I can execute scripts via terminal?

I have installed OpenMP: brew install clang-omp

Answer 1

• install clang-omp

  brew install clang-omp
  

• make sure you xcode command line tool

  xcode-select --install
  

• I actually had one error while running a sample openmp code

  /usr/local/opt/libiomp/include/libiomp/omp.h:139:21: error: expected ';' after top level declarator extern void   __ KAI_KMPC_CONVENTION kmp_set_stacksize_s        (size_t);
  

• Just remove one space that is present between __ and KAI from the file

• Now use the command

  clang-omp -fopenmp helloopenmp.c
  

  and run the following code

  #include 
  #include 
  int main() {
      #pragma omp parallel
      printf("Hello from thread %d, nthreads %d\n", omp_get_thread_num(), omp_get_num_threads());
  }
  

• You should get output similar to this

  Hello from thread 3, nthreads 4
  Hello from thread 2, nthreads 4
  Hello from thread 0, nthreads 4
  Hello from thread 1, nthreads 4
  

• Worked on OS X 10.11.3 and with brew update dated 18th Feb 2016