002dSaving-Plans.html#Words-of-Wisdom_002dSaving-Plans">Words of Wisdom-Saving Plans</a>.
</p>
<a name="Planning_002drigor-flags"></a>
<h4 class="subsubheading">Planning-rigor flags</h4>
<ul>
<li> <a name="index-FFTW_005fESTIMATE-2"></a>
<code>FFTW_ESTIMATE</code> specifies that, instead of actual measurements of
different algorithms, a simple heuristic is used to pick a (probably
sub-optimal) plan quickly.  With this flag, the input/output arrays are
not overwritten during planning.

</li><li> <a name="ind