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Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents 2cd0e3b3e1fd
children
rev   line source
Chris@42 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Chris@42 2 <html>
Chris@42 3 <!-- This manual is for FFTW
Chris@42 4 (version 3.3.5, 30 July 2016).
Chris@42 5
Chris@42 6 Copyright (C) 2003 Matteo Frigo.
Chris@42 7
Chris@42 8 Copyright (C) 2003 Massachusetts Institute of Technology.
Chris@42 9
Chris@42 10 Permission is granted to make and distribute verbatim copies of this
Chris@42 11 manual provided the copyright notice and this permission notice are
Chris@42 12 preserved on all copies.
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Chris@42 14 Permission is granted to copy and distribute modified versions of this
Chris@42 15 manual under the conditions for verbatim copying, provided that the
Chris@42 16 entire resulting derived work is distributed under the terms of a
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Chris@42 21 except that this permission notice may be stated in a translation
Chris@42 22 approved by the Free Software Foundation. -->
Chris@42 23 <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: 64-bit Guru Interface</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: 64-bit Guru Interface">
Chris@42 28 <meta name="keywords" content="FFTW 3.3.5: 64-bit Guru Interface">
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Chris@42 33 <link href="index.html#Top" rel="start" title="Top">
Chris@42 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Guru-Interface.html#Guru-Interface" rel="up" title="Guru Interface">
Chris@42 37 <link href="New_002darray-Execute-Functions.html#New_002darray-Execute-Functions" rel="next" title="New-array Execute Functions">
Chris@42 38 <link href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" rel="prev" title="Guru Real-to-real Transforms">
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Chris@42 67
Chris@42 68
Chris@42 69 </head>
Chris@42 70
Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="g_t64_002dbit-Guru-Interface"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 Previous: <a href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" accesskey="p" rel="prev">Guru Real-to-real Transforms</a>, Up: <a href="Guru-Interface.html#Guru-Interface" accesskey="u" rel="up">Guru Interface</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
Chris@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="g_t64_002dbit-Guru-Interface-1"></a>
Chris@42 79 <h4 class="subsection">4.5.6 64-bit Guru Interface</h4>
Chris@42 80 <a name="index-64_002dbit-architecture"></a>
Chris@42 81
Chris@42 82 <p>When compiled in 64-bit mode on a 64-bit architecture (where addresses
Chris@42 83 are 64 bits wide), FFTW uses 64-bit quantities internally for all
Chris@42 84 transform sizes, strides, and so on&mdash;you don&rsquo;t have to do anything
Chris@42 85 special to exploit this. However, in the ordinary FFTW interfaces,
Chris@42 86 you specify the transform size by an <code>int</code> quantity, which is
Chris@42 87 normally only 32 bits wide. This means that, even though FFTW is
Chris@42 88 using 64-bit sizes internally, you cannot specify a single transform
Chris@42 89 dimension larger than
Chris@42 90 2<sup><small>31</small></sup>&minus;1numbers.
Chris@42 91 </p>
Chris@42 92 <p>We expect that few users will require transforms larger than this, but,
Chris@42 93 for those who do, we provide a 64-bit version of the guru interface in
Chris@42 94 which all sizes are specified as integers of type <code>ptrdiff_t</code>
Chris@42 95 instead of <code>int</code>. (<code>ptrdiff_t</code> is a signed integer type
Chris@42 96 defined by the C standard to be wide enough to represent address
Chris@42 97 differences, and thus must be at least 64 bits wide on a 64-bit
Chris@42 98 machine.) We stress that there is <em>no performance advantage</em> to
Chris@42 99 using this interface&mdash;the same internal FFTW code is employed
Chris@42 100 regardless&mdash;and it is only necessary if you want to specify very
Chris@42 101 large transform sizes.
Chris@42 102 <a name="index-ptrdiff_005ft"></a>
Chris@42 103 </p>
Chris@42 104
Chris@42 105 <p>In particular, the 64-bit guru interface is a set of planner routines
Chris@42 106 that are exactly the same as the guru planner routines, except that
Chris@42 107 they are named with &lsquo;<samp>guru64</samp>&rsquo; instead of &lsquo;<samp>guru</samp>&rsquo; and they take
Chris@42 108 arguments of type <code>fftw_iodim64</code> instead of <code>fftw_iodim</code>.
Chris@42 109 For example, instead of <code>fftw_plan_guru_dft</code>, we have
Chris@42 110 <code>fftw_plan_guru64_dft</code>.
Chris@42 111 </p>
Chris@42 112 <div class="example">
Chris@42 113 <pre class="example">fftw_plan fftw_plan_guru64_dft(
Chris@42 114 int rank, const fftw_iodim64 *dims,
Chris@42 115 int howmany_rank, const fftw_iodim64 *howmany_dims,
Chris@42 116 fftw_complex *in, fftw_complex *out,
Chris@42 117 int sign, unsigned flags);
Chris@42 118 </pre></div>
Chris@42 119 <a name="index-fftw_005fplan_005fguru64_005fdft"></a>
Chris@42 120
Chris@42 121 <p>The <code>fftw_iodim64</code> type is similar to <code>fftw_iodim</code>, with the
Chris@42 122 same interpretation, except that it uses type <code>ptrdiff_t</code> instead
Chris@42 123 of type <code>int</code>.
Chris@42 124 </p>
Chris@42 125 <div class="example">
Chris@42 126 <pre class="example">typedef struct {
Chris@42 127 ptrdiff_t n;
Chris@42 128 ptrdiff_t is;
Chris@42 129 ptrdiff_t os;
Chris@42 130 } fftw_iodim64;
Chris@42 131 </pre></div>
Chris@42 132 <a name="index-fftw_005fiodim64"></a>
Chris@42 133
Chris@42 134 <p>Every other &lsquo;<samp>fftw_plan_guru</samp>&rsquo; function also has a
Chris@42 135 &lsquo;<samp>fftw_plan_guru64</samp>&rsquo; equivalent, but we do not repeat their
Chris@42 136 documentation here since they are identical to the 32-bit versions
Chris@42 137 except as noted above.
Chris@42 138 </p>
Chris@42 139 <hr>
Chris@42 140 <div class="header">
Chris@42 141 <p>
Chris@42 142 Previous: <a href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" accesskey="p" rel="prev">Guru Real-to-real Transforms</a>, Up: <a href="Guru-Interface.html#Guru-Interface" accesskey="u" rel="up">Guru Interface</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
Chris@42 143 </div>
Chris@42 144
Chris@42 145
Chris@42 146
Chris@42 147 </body>
Chris@42 148 </html>