mirror of
https://github.com/tildearrow/furnace.git
synced 2024-11-30 16:33:01 +00:00
91 lines
4.2 KiB
HTML
91 lines
4.2 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- This manual is for FFTW
|
|
(version 3.3.10, 10 December 2020).
|
|
|
|
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. -->
|
|
<!-- Created by GNU Texinfo 6.7, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<title>Column-major Format (FFTW 3.3.10)</title>
|
|
|
|
<meta name="description" content="Column-major Format (FFTW 3.3.10)">
|
|
<meta name="keywords" content="Column-major Format (FFTW 3.3.10)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<link href="index.html" rel="start" title="Top">
|
|
<link href="Concept-Index.html" rel="index" title="Concept Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="Multi_002ddimensional-Array-Format.html" rel="up" title="Multi-dimensional Array Format">
|
|
<link href="Fixed_002dsize-Arrays-in-C.html" rel="next" title="Fixed-size Arrays in C">
|
|
<link href="Row_002dmajor-Format.html" rel="prev" title="Row-major Format">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<span id="Column_002dmajor-Format"></span><div class="header">
|
|
<p>
|
|
Next: <a href="Fixed_002dsize-Arrays-in-C.html" accesskey="n" rel="next">Fixed-size Arrays in C</a>, Previous: <a href="Row_002dmajor-Format.html" accesskey="p" rel="prev">Row-major Format</a>, Up: <a href="Multi_002ddimensional-Array-Format.html" accesskey="u" rel="up">Multi-dimensional Array Format</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<span id="Column_002dmajor-Format-1"></span><h4 class="subsection">3.2.2 Column-major Format</h4>
|
|
<span id="index-column_002dmajor"></span>
|
|
|
|
<p>Readers from the Fortran world are used to arrays stored in
|
|
<em>column-major</em> order (sometimes called “Fortran order”). This is
|
|
essentially the exact opposite of row-major order in that, here, the
|
|
<em>first</em> dimension’s index varies most quickly.
|
|
</p>
|
|
<p>If you have an array stored in column-major order and wish to
|
|
transform it using FFTW, it is quite easy to do. When creating the
|
|
plan, simply pass the dimensions of the array to the planner in
|
|
<em>reverse order</em>. For example, if your array is a rank three
|
|
<code>N x M x L</code> matrix in column-major order, you should pass the
|
|
dimensions of the array as if it were an <code>L x M x N</code> matrix
|
|
(which it is, from the perspective of FFTW). This is done for you
|
|
<em>automatically</em> by the FFTW legacy-Fortran interface
|
|
(see <a href="Calling-FFTW-from-Legacy-Fortran.html">Calling FFTW from Legacy Fortran</a>), but you must do it
|
|
manually with the modern Fortran interface (see <a href="Reversing-array-dimensions.html">Reversing array dimensions</a>).
|
|
<span id="index-Fortran-interface"></span>
|
|
</p>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|