Exercise: Hello World!

We start with a warm-up exercise. 

Copy the HELLO folder from the teacher's account. In there you will find simple parallel "Hello World"-type programs in OpenMP and MPI for both C and Fortran. You will need the "intel" and "intelmpi" modules for this to work

$ module load intel intelmpi

Typing "make" will build the binaries.

1. Compile and run the OpenMP version of the program:
   
   

   $ cd ~/HELLO/omp
   $ make
   $ OMP_NUM_THREADS=4 ./HELLO_C.exe 

   Something is obviously wrong. Fix it!
   
   
2. Compile and run the MPI version of the program (this is only possible within a batch job - see the introduction):
   
   

   $ cd ~/HELLO/mpi
   $ make
   $ mpirun -np 4 ./HELLO_C.exe

   Modify the code so that each process sends its own rank to process 0, which then prints all the ranks.