Computational Physics Lectures: How to optimize codes, from vectorization to parallelization

Some of the most important MPI functions

$MPI\_Init$ - initiate an MPI computation
$MPI\_Finalize$ - terminate the MPI computation and clean up
$MPI\_Comm\_size$ - how many processes participate in a given MPI communicator?
$MPI\_Comm\_rank$ - which one am I? (A number between 0 and size-1.)
$MPI\_Send$ - send a message to a particular process within an MPI communicator
$MPI\_Recv$ - receive a message from a particular process within an MPI communicator
$MPI\_reduce$ or $MPI\_Allreduce$ , send and receive messages