ialize the MPI environment.</p>
<p>If the MPI environment has not already been initialized, initializes MPI with a call to <code class="computeroutput">MPI_Init</code>. Since this constructor does not take command-line arguments (<code class="computeroutput">argc</code> and <code class="computeroutput">argv</code>), it is only available when the underlying MPI implementation supports calling <code class="computeroutput">MPI_Init</code> with <code class="computeroutput">NULL</code> arguments, indicated by th