y executed by calling
<code>fftw_execute</code> on the plan, as usual. 
<a name="index-fftw_005fexecute-401"></a>

   <p>The <code>flags</code> are the usual FFTW planner flags, but support
two additional flags: <code>FFTW_MPI_TRANSPOSED_OUT</code> and/or
<code>FFTW_MPI_TRANSPOSED_IN</code>.  What these flags indicate, for
transpose plans, is that the output and/or input, respectively, are
<em>locally</em> transposed.  That is, on each process input data is
normally stored as a <code>local_n0</code> by <cod