exampleMPI1.c and exampleMPI2.cc do the same computation.
exampleMPI1 is a C version
exampleMPI2 is a C++ version

make clean
make
mpirun -np 4 ./exampleMPI1
mpirun -np 4 ./exampleMPI1_cad
mpirun -np 4 ./exampleMPI2
mpirun -np 4 ./exampleMPI2_cad
