OpenMP directives
---------------------

Since no loop-level constructs are used, only a small number
of OpenMP 4.5 directives are relevant and needed.  The most
important ones are listed here and detailed in subsections:

   * ``!$omp target``/``!$omp end target`` is analogous to 
     ``!$omp parallel``, in that it defines  a section of the
     code that will be executed on the GPU
   * ``!$omp teams`` is used to set the number of GPU threads
     that execute in parallel in a thread block
   * ``!$omp declare target (v1, v2, ...)`` is used to specify
     if an array should exist only on the GPU, or should exist
     on both the GPU and CPU
   * ``!$omp target update`` is used to update (synchronize)
     data on the GPU and CPU

.. toctree::
   :maxdepth: 4

   target
   team
   declare_target
   target_update