lizable or has an associated MPI data type. One can think of this operation as a <code class="computeroutput">gather</code> to the <code class="computeroutput">root</code>, followed by an <code class="computeroutput">std::accumulate()</code> over the gathered values and using the operation <code class="computeroutput">op</code>.</p>
<p>When the type <code class="computeroutput">T</code> has an associated MPI data type, this routine invokes <code class="computeroutput">MPI_Reduce</code> to perform the reduct