Mercurial > hg > batch-feature-extraction-tool
diff Lib/fftw-3.2.1/doc/html/.svn/text-base/Planner-Flags.html.svn-base @ 15:585caf503ef5 tip
Tidy up for ROLI
| author | Geogaddi\David <d.m.ronan@qmul.ac.uk> |
|---|---|
| date | Tue, 17 May 2016 18:50:19 +0100 |
| parents | 636c989477e7 |
| children |
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--- a/Lib/fftw-3.2.1/doc/html/.svn/text-base/Planner-Flags.html.svn-base Wed May 04 11:02:59 2016 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,169 +0,0 @@ -<html lang="en"> -<head> -<title>Planner Flags - FFTW 3.2.1</title> -<meta http-equiv="Content-Type" content="text/html"> -<meta name="description" content="FFTW 3.2.1"> -<meta name="generator" content="makeinfo 4.8"> -<link title="Top" rel="start" href="index.html#Top"> -<link rel="up" href="Basic-Interface.html#Basic-Interface" title="Basic Interface"> -<link rel="prev" href="Complex-DFTs.html#Complex-DFTs" title="Complex DFTs"> -<link rel="next" href="Real_002ddata-DFTs.html#Real_002ddata-DFTs" title="Real-data DFTs"> -<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> -<!-- -This manual is for FFTW -(version 3.2.1, 5 February 2009). - -Copyright (C) 2003 Matteo Frigo. - -Copyright (C) 2003 Massachusetts Institute of Technology. - - Permission is granted to make and distribute verbatim copies of - this manual provided the copyright notice and this permission - notice are preserved on all copies. - - Permission is granted to copy and distribute modified versions of - this manual under the conditions for verbatim copying, provided - that the entire resulting derived work is distributed under the - terms of a permission notice identical to this one. - - Permission is granted to copy and distribute translations of this - manual into another language, under the above conditions for - modified versions, except that this permission notice may be - stated in a translation approved by the Free Software Foundation. - --> -<meta http-equiv="Content-Style-Type" content="text/css"> -<style type="text/css"><!-- - pre.display { font-family:inherit } - pre.format { font-family:inherit } - pre.smalldisplay { font-family:inherit; font-size:smaller } - pre.smallformat { font-family:inherit; font-size:smaller } - pre.smallexample { font-size:smaller } - pre.smalllisp { font-size:smaller } - span.sc { font-variant:small-caps } - span.roman { font-family:serif; font-weight:normal; } - span.sansserif { font-family:sans-serif; font-weight:normal; } ---></style> -</head> -<body> -<div class="node"> -<p> -<a name="Planner-Flags"></a> -Next: <a rel="next" accesskey="n" href="Real_002ddata-DFTs.html#Real_002ddata-DFTs">Real-data DFTs</a>, -Previous: <a rel="previous" accesskey="p" href="Complex-DFTs.html#Complex-DFTs">Complex DFTs</a>, -Up: <a rel="up" accesskey="u" href="Basic-Interface.html#Basic-Interface">Basic Interface</a> -<hr> -</div> - -<h4 class="subsection">4.3.2 Planner Flags</h4> - -<p>All of the planner routines in FFTW accept an integer <code>flags</code> -argument, which is a bitwise OR (`<samp><span class="samp">|</span></samp>') of zero or more of the flag -constants defined below. These flags control the rigor (and time) of -the planning process, and can also impose (or lift) restrictions on the -type of transform algorithm that is employed. - - <p><em>Important:</em> the planner overwrites the input array during -planning unless a saved plan (see <a href="Wisdom.html#Wisdom">Wisdom</a>) is available for that -problem, so you should initialize your input data after creating the -plan. The only exceptions to this are the <code>FFTW_ESTIMATE</code> and -<code>FFTW_WISDOM_ONLY</code> flags, as mentioned below. - - <p>In all cases, if wisdom is available for the given problem that was -created with equal-or-greater planning rigor, then it is used instead. -For example, in <code>FFTW_ESTIMATE</code> mode any available wisdom is -used, whereas in <code>FFTW_PATIENT</code> mode only wisdom created in -patient or exhaustive mode can be used. See <a href="Words-of-Wisdom_002dSaving-Plans.html#Words-of-Wisdom_002dSaving-Plans">Words of Wisdom-Saving Plans</a>. - -<h5 class="subsubheading">Planning-rigor flags</h5> - - <ul> -<li><a name="index-FFTW_005fESTIMATE-162"></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><a name="index-FFTW_005fMEASURE-163"></a><code>FFTW_MEASURE</code> tells FFTW to find an optimized plan by actually -<em>computing</em> several FFTs and measuring their execution time. -Depending on your machine, this can take some time (often a few -seconds). <code>FFTW_MEASURE</code> is the default planning option. - - <li><a name="index-FFTW_005fPATIENT-164"></a><code>FFTW_PATIENT</code> is like <code>FFTW_MEASURE</code>, but considers a wider -range of algorithms and often produces a “more optimal” plan -(especially for large transforms), but at the expense of several times -longer planning time (especially for large transforms). - - <li><a name="index-FFTW_005fEXHAUSTIVE-165"></a><code>FFTW_EXHAUSTIVE</code> is like <code>FFTW_PATIENT</code>, but considers an -even wider range of algorithms, including many that we think are -unlikely to be fast, to produce the most optimal plan but with a -substantially increased planning time. - - <li><a name="index-FFTW_005fWISDOM_005fONLY-166"></a><code>FFTW_WISDOM_ONLY</code> is a special planning mode in which the plan -is only created if wisdom is available for the given problem, and -otherwise a <code>NULL</code> plan is returned. This can be combined with -other flags, e.g. `<samp><span class="samp">FFTW_WISDOM_ONLY | FFTW_PATIENT</span></samp>' creates a -plan only if wisdom is available that was created in -<code>FFTW_PATIENT</code> or <code>FFTW_EXHAUSTIVE</code> mode. The -<code>FFTW_WISDOM_ONLY</code> flag is intended for users who need to detect -whether wisdom is available; for example, if wisdom is not available -one may wish to allocate new arrays for planning so that user data is -not overwritten. - -</ul> - -<h5 class="subsubheading">Algorithm-restriction flags</h5> - - <ul> -<li><a name="index-FFTW_005fDESTROY_005fINPUT-167"></a><code>FFTW_DESTROY_INPUT</code> specifies that an out-of-place transform is -allowed to <em>overwrite its input</em> array with arbitrary data; this -can sometimes allow more efficient algorithms to be employed. -<a name="index-out_002dof_002dplace-168"></a> -<li><a name="index-FFTW_005fPRESERVE_005fINPUT-169"></a><code>FFTW_PRESERVE_INPUT</code> specifies that an out-of-place transform must -<em>not change its input</em> array. This is ordinarily the -<em>default</em>, except for c2r and hc2r (i.e. complex-to-real) -transforms for which <code>FFTW_DESTROY_INPUT</code> is the default. In the -latter cases, passing <code>FFTW_PRESERVE_INPUT</code> will attempt to use -algorithms that do not destroy the input, at the expense of worse -performance; for multi-dimensional c2r transforms, however, no -input-preserving algorithms are implemented and the planner will return -<code>NULL</code> if one is requested. -<a name="index-c2r-170"></a><a name="index-hc2r-171"></a> -<li><a name="index-FFTW_005fUNALIGNED-172"></a><a name="index-alignment-173"></a><code>FFTW_UNALIGNED</code> specifies that the algorithm may not impose any -unusual alignment requirements on the input/output arrays (i.e. no -SIMD may be used). This flag is normally <em>not necessary</em>, since -the planner automatically detects misaligned arrays. The only use for -this flag is if you want to use the new-array execute interface to -execute a given plan on a different array that may not be aligned like -the original. (Using <code>fftw_malloc</code> makes this flag unnecessary -even then.) - -</ul> - -<h5 class="subsubheading">Limiting planning time</h5> - -<pre class="example"> extern void fftw_set_timelimit(double seconds); -</pre> - <p><a name="index-fftw_005fset_005ftimelimit-174"></a> -This function instructs FFTW to spend at most <code>seconds</code> seconds -(approximately) in the planner. If <code>seconds == -FFTW_NO_TIMELIMIT</code> (the default value, which is negative), then -planning time is unbounded. Otherwise, FFTW plans with a -progressively wider range of algorithms until the the given time limit -is reached or the given range of algorithms is explored, returning the -best available plan. -<a name="index-FFTW_005fNO_005fTIMELIMIT-175"></a> -For example, specifying <code>FFTW_PATIENT</code> first plans in -<code>FFTW_ESTIMATE</code> mode, then in <code>FFTW_MEASURE</code> mode, then -finally (time permitting) in <code>FFTW_PATIENT</code>. If -<code>FFTW_EXHAUSTIVE</code> is specified instead, the planner will further -progress to <code>FFTW_EXHAUSTIVE</code> mode. - - <p>Note that the <code>seconds</code> argument specifies only a rough limit; in -practice, the planner may use somewhat more time if the time limit is -reached when the planner is in the middle of an operation that cannot -be interrupted. At the very least, the planner will complete planning -in <code>FFTW_ESTIMATE</code> mode (which is thus equivalent to a time limit -of 0). - -<!-- =========> --> -</body></html> -