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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 19 Nov 2019 14:52:55 +0000 (2019-11-19)
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1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2 <html>
3 <!-- This manual is for FFTW
4 (version 3.3.8, 24 May 2018).
5
6 Copyright (C) 2003 Matteo Frigo.
7
8 Copyright (C) 2003 Massachusetts Institute of Technology.
9
10 Permission is granted to make and distribute verbatim copies of this
11 manual provided the copyright notice and this permission notice are
12 preserved on all copies.
13
14 Permission is granted to copy and distribute modified versions of this
15 manual under the conditions for verbatim copying, provided that the
16 entire resulting derived work is distributed under the terms of a
17 permission notice identical to this one.
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19 Permission is granted to copy and distribute translations of this manual
20 into another language, under the above conditions for modified versions,
21 except that this permission notice may be stated in a translation
22 approved by the Free Software Foundation. -->
23 <!-- Created by GNU Texinfo 6.3, http://www.gnu.org/software/texinfo/ -->
24 <head>
25 <title>FFTW 3.3.8: 64-bit Guru Interface</title>
26
27 <meta name="description" content="FFTW 3.3.8: 64-bit Guru Interface">
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35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
36 <link href="Guru-Interface.html#Guru-Interface" rel="up" title="Guru Interface">
37 <link href="New_002darray-Execute-Functions.html#New_002darray-Execute-Functions" rel="next" title="New-array Execute Functions">
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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68 </head>
69
70 <body lang="en">
71 <a name="g_t64_002dbit-Guru-Interface"></a>
72 <div class="header">
73 <p>
74 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>
75 </div>
76 <hr>
77 <a name="g_t64_002dbit-Guru-Interface-1"></a>
78 <h4 class="subsection">4.5.6 64-bit Guru Interface</h4>
79 <a name="index-64_002dbit-architecture"></a>
80
81 <p>When compiled in 64-bit mode on a 64-bit architecture (where addresses
82 are 64 bits wide), FFTW uses 64-bit quantities internally for all
83 transform sizes, strides, and so on&mdash;you don&rsquo;t have to do anything
84 special to exploit this. However, in the ordinary FFTW interfaces,
85 you specify the transform size by an <code>int</code> quantity, which is
86 normally only 32 bits wide. This means that, even though FFTW is
87 using 64-bit sizes internally, you cannot specify a single transform
88 dimension larger than
89 2<sup><small>31</small></sup>&minus;1
90 numbers.
91 </p>
92 <p>We expect that few users will require transforms larger than this, but,
93 for those who do, we provide a 64-bit version of the guru interface in
94 which all sizes are specified as integers of type <code>ptrdiff_t</code>
95 instead of <code>int</code>. (<code>ptrdiff_t</code> is a signed integer type
96 defined by the C standard to be wide enough to represent address
97 differences, and thus must be at least 64 bits wide on a 64-bit
98 machine.) We stress that there is <em>no performance advantage</em> to
99 using this interface&mdash;the same internal FFTW code is employed
100 regardless&mdash;and it is only necessary if you want to specify very
101 large transform sizes.
102 <a name="index-ptrdiff_005ft"></a>
103 </p>
104
105 <p>In particular, the 64-bit guru interface is a set of planner routines
106 that are exactly the same as the guru planner routines, except that
107 they are named with &lsquo;<samp>guru64</samp>&rsquo; instead of &lsquo;<samp>guru</samp>&rsquo; and they take
108 arguments of type <code>fftw_iodim64</code> instead of <code>fftw_iodim</code>.
109 For example, instead of <code>fftw_plan_guru_dft</code>, we have
110 <code>fftw_plan_guru64_dft</code>.
111 </p>
112 <div class="example">
113 <pre class="example">fftw_plan fftw_plan_guru64_dft(
114 int rank, const fftw_iodim64 *dims,
115 int howmany_rank, const fftw_iodim64 *howmany_dims,
116 fftw_complex *in, fftw_complex *out,
117 int sign, unsigned flags);
118 </pre></div>
119 <a name="index-fftw_005fplan_005fguru64_005fdft"></a>
120
121 <p>The <code>fftw_iodim64</code> type is similar to <code>fftw_iodim</code>, with the
122 same interpretation, except that it uses type <code>ptrdiff_t</code> instead
123 of type <code>int</code>.
124 </p>
125 <div class="example">
126 <pre class="example">typedef struct {
127 ptrdiff_t n;
128 ptrdiff_t is;
129 ptrdiff_t os;
130 } fftw_iodim64;
131 </pre></div>
132 <a name="index-fftw_005fiodim64"></a>
133
134 <p>Every other &lsquo;<samp>fftw_plan_guru</samp>&rsquo; function also has a
135 &lsquo;<samp>fftw_plan_guru64</samp>&rsquo; equivalent, but we do not repeat their
136 documentation here since they are identical to the 32-bit versions
137 except as noted above.
138 </p>
139 <hr>
140 <div class="header">
141 <p>
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>
143 </div>
144
145
146
147 </body>
148 </html>