ame order</em> from <em>every</em>
process in a given communicator.  (For example, <code>MPI_Barrier</code> is
the canonical example of a collective function in the MPI standard.)
<a name="index-collective-function-2"></a>
<a name="index-MPI_005fBarrier"></a>
</p>

<p>The functions in FFTW that are <em>always</em> collective are: every
function beginning with &lsquo;<samp>fftw_mpi_plan</samp>&rsquo;, as well as
<code>fftw_mpi_broadcast_wisdom</code> and <code>fftw_mpi_gather_wisdom</code>.
Also, the followi