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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
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cannam@167 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
cannam@167 2 <html>
cannam@167 3 <!-- This manual is for FFTW
cannam@167 4 (version 3.3.8, 24 May 2018).
cannam@167 5
cannam@167 6 Copyright (C) 2003 Matteo Frigo.
cannam@167 7
cannam@167 8 Copyright (C) 2003 Massachusetts Institute of Technology.
cannam@167 9
cannam@167 10 Permission is granted to make and distribute verbatim copies of this
cannam@167 11 manual provided the copyright notice and this permission notice are
cannam@167 12 preserved on all copies.
cannam@167 13
cannam@167 14 Permission is granted to copy and distribute modified versions of this
cannam@167 15 manual under the conditions for verbatim copying, provided that the
cannam@167 16 entire resulting derived work is distributed under the terms of a
cannam@167 17 permission notice identical to this one.
cannam@167 18
cannam@167 19 Permission is granted to copy and distribute translations of this manual
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cannam@167 21 except that this permission notice may be stated in a translation
cannam@167 22 approved by the Free Software Foundation. -->
cannam@167 23 <!-- Created by GNU Texinfo 6.3, http://www.gnu.org/software/texinfo/ -->
cannam@167 24 <head>
cannam@167 25 <title>FFTW 3.3.8: Column-major Format</title>
cannam@167 26
cannam@167 27 <meta name="description" content="FFTW 3.3.8: Column-major Format">
cannam@167 28 <meta name="keywords" content="FFTW 3.3.8: Column-major Format">
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cannam@167 33 <link href="index.html#Top" rel="start" title="Top">
cannam@167 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
cannam@167 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
cannam@167 36 <link href="Multi_002ddimensional-Array-Format.html#Multi_002ddimensional-Array-Format" rel="up" title="Multi-dimensional Array Format">
cannam@167 37 <link href="Fixed_002dsize-Arrays-in-C.html#Fixed_002dsize-Arrays-in-C" rel="next" title="Fixed-size Arrays in C">
cannam@167 38 <link href="Row_002dmajor-Format.html#Row_002dmajor-Format" rel="prev" title="Row-major Format">
cannam@167 39 <style type="text/css">
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cannam@167 66
cannam@167 67
cannam@167 68 </head>
cannam@167 69
cannam@167 70 <body lang="en">
cannam@167 71 <a name="Column_002dmajor-Format"></a>
cannam@167 72 <div class="header">
cannam@167 73 <p>
cannam@167 74 Next: <a href="Fixed_002dsize-Arrays-in-C.html#Fixed_002dsize-Arrays-in-C" accesskey="n" rel="next">Fixed-size Arrays in C</a>, Previous: <a href="Row_002dmajor-Format.html#Row_002dmajor-Format" accesskey="p" rel="prev">Row-major Format</a>, Up: <a href="Multi_002ddimensional-Array-Format.html#Multi_002ddimensional-Array-Format" accesskey="u" rel="up">Multi-dimensional Array Format</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>
cannam@167 75 </div>
cannam@167 76 <hr>
cannam@167 77 <a name="Column_002dmajor-Format-1"></a>
cannam@167 78 <h4 class="subsection">3.2.2 Column-major Format</h4>
cannam@167 79 <a name="index-column_002dmajor"></a>
cannam@167 80
cannam@167 81 <p>Readers from the Fortran world are used to arrays stored in
cannam@167 82 <em>column-major</em> order (sometimes called &ldquo;Fortran order&rdquo;). This is
cannam@167 83 essentially the exact opposite of row-major order in that, here, the
cannam@167 84 <em>first</em> dimension&rsquo;s index varies most quickly.
cannam@167 85 </p>
cannam@167 86 <p>If you have an array stored in column-major order and wish to
cannam@167 87 transform it using FFTW, it is quite easy to do. When creating the
cannam@167 88 plan, simply pass the dimensions of the array to the planner in
cannam@167 89 <em>reverse order</em>. For example, if your array is a rank three
cannam@167 90 <code>N x M x L</code> matrix in column-major order, you should pass the
cannam@167 91 dimensions of the array as if it were an <code>L x M x N</code> matrix
cannam@167 92 (which it is, from the perspective of FFTW). This is done for you
cannam@167 93 <em>automatically</em> by the FFTW legacy-Fortran interface
cannam@167 94 (see <a href="Calling-FFTW-from-Legacy-Fortran.html#Calling-FFTW-from-Legacy-Fortran">Calling FFTW from Legacy Fortran</a>), but you must do it
cannam@167 95 manually with the modern Fortran interface (see <a href="Reversing-array-dimensions.html#Reversing-array-dimensions">Reversing array dimensions</a>).
cannam@167 96 <a name="index-Fortran-interface"></a>
cannam@167 97 </p>
cannam@167 98
cannam@167 99
cannam@167 100
cannam@167 101 </body>
cannam@167 102 </html>