#include <cmath>
int main()
{
        const int size = 256;
        double sinTable[size];

        #pragma omp parallel for
        for(int n=0; n<size; ++n)
                sinTable[n] = std::sin(2 * M_PI * n / size);

        // the table is now initialized
}

ld: library not found for -lgomp
clang: error: linker command failed with exit code 1 (use -v to see invocation)

brew install llvm
brew install libomp

/usr/local/Cellar/llvm/(llvm version)/bin/clang
                -fopenmp=libomp ~/openmp_program.c