Mercurial > hg > sv-dependency-builds

annotate src/fftw-3.3.3/doc/html/Column_002dmajor-Format.html @ 83:ae30d91d2ffe

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
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 37bf6b4a2645
children
rev   line source
Chris@10 1 <html lang="en">
Chris@10 2 <head>
Chris@10 3 <title>Column-major Format - FFTW 3.3.3</title>
Chris@10 4 <meta http-equiv="Content-Type" content="text/html">
Chris@10 5 <meta name="description" content="FFTW 3.3.3">
Chris@10 6 <meta name="generator" content="makeinfo 4.13">
Chris@10 7 <link title="Top" rel="start" href="index.html#Top">
Chris@10 8 <link rel="up" href="Multi_002ddimensional-Array-Format.html#Multi_002ddimensional-Array-Format" title="Multi-dimensional Array Format">
Chris@10 9 <link rel="prev" href="Row_002dmajor-Format.html#Row_002dmajor-Format" title="Row-major Format">
Chris@10 10 <link rel="next" href="Fixed_002dsize-Arrays-in-C.html#Fixed_002dsize-Arrays-in-C" title="Fixed-size Arrays in C">
Chris@10 11 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
Chris@10 12 <!--
Chris@10 13 This manual is for FFTW
Chris@10 14 (version 3.3.3, 25 November 2012).
Chris@10 15
Chris@10 16 Copyright (C) 2003 Matteo Frigo.
Chris@10 17
Chris@10 18 Copyright (C) 2003 Massachusetts Institute of Technology.
Chris@10 19
Chris@10 20 Permission is granted to make and distribute verbatim copies of
Chris@10 21 this manual provided the copyright notice and this permission
Chris@10 22 notice are preserved on all copies.
Chris@10 23
Chris@10 24 Permission is granted to copy and distribute modified versions of
Chris@10 25 this manual under the conditions for verbatim copying, provided
Chris@10 26 that the entire resulting derived work is distributed under the
Chris@10 27 terms of a permission notice identical to this one.
Chris@10 28
Chris@10 29 Permission is granted to copy and distribute translations of this
Chris@10 30 manual into another language, under the above conditions for
Chris@10 31 modified versions, except that this permission notice may be
Chris@10 32 stated in a translation approved by the Free Software Foundation.
Chris@10 33 -->
Chris@10 34 <meta http-equiv="Content-Style-Type" content="text/css">
Chris@10 35 <style type="text/css"><!--
Chris@10 36 pre.display { font-family:inherit }
Chris@10 37 pre.format { font-family:inherit }
Chris@10 38 pre.smalldisplay { font-family:inherit; font-size:smaller }
Chris@10 39 pre.smallformat { font-family:inherit; font-size:smaller }
Chris@10 40 pre.smallexample { font-size:smaller }
Chris@10 41 pre.smalllisp { font-size:smaller }
Chris@10 42 span.sc { font-variant:small-caps }
Chris@10 43 span.roman { font-family:serif; font-weight:normal; }
Chris@10 44 span.sansserif { font-family:sans-serif; font-weight:normal; }
Chris@10 45 --></style>
Chris@10 46 </head>
Chris@10 47 <body>
Chris@10 48 <div class="node">
Chris@10 49 <a name="Column-major-Format"></a>
Chris@10 50 <a name="Column_002dmajor-Format"></a>
Chris@10 51 <p>
Chris@10 52 Next:&nbsp;<a rel="next" accesskey="n" href="Fixed_002dsize-Arrays-in-C.html#Fixed_002dsize-Arrays-in-C">Fixed-size Arrays in C</a>,
Chris@10 53 Previous:&nbsp;<a rel="previous" accesskey="p" href="Row_002dmajor-Format.html#Row_002dmajor-Format">Row-major Format</a>,
Chris@10 54 Up:&nbsp;<a rel="up" accesskey="u" href="Multi_002ddimensional-Array-Format.html#Multi_002ddimensional-Array-Format">Multi-dimensional Array Format</a>
Chris@10 55 <hr>
Chris@10 56 </div>
Chris@10 57
Chris@10 58 <h4 class="subsection">3.2.2 Column-major Format</h4>
Chris@10 59
Chris@10 60 <p><a name="index-column_002dmajor-118"></a>
Chris@10 61 Readers from the Fortran world are used to arrays stored in
Chris@10 62 <dfn>column-major</dfn> order (sometimes called &ldquo;Fortran order&rdquo;). This is
Chris@10 63 essentially the exact opposite of row-major order in that, here, the
Chris@10 64 <em>first</em> dimension's index varies most quickly.
Chris@10 65
Chris@10 66 <p>If you have an array stored in column-major order and wish to
Chris@10 67 transform it using FFTW, it is quite easy to do. When creating the
Chris@10 68 plan, simply pass the dimensions of the array to the planner in
Chris@10 69 <em>reverse order</em>. For example, if your array is a rank three
Chris@10 70 <code>N x M x L</code> matrix in column-major order, you should pass the
Chris@10 71 dimensions of the array as if it were an <code>L x M x N</code> matrix
Chris@10 72 (which it is, from the perspective of FFTW). This is done for you
Chris@10 73 <em>automatically</em> by the FFTW legacy-Fortran interface
Chris@10 74 (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
Chris@10 75 manually with the modern Fortran interface (see <a href="Reversing-array-dimensions.html#Reversing-array-dimensions">Reversing array dimensions</a>).
Chris@10 76 <a name="index-Fortran-interface-119"></a>
Chris@10 77 <!-- =========> -->
Chris@10 78
Chris@10 79 </body></html>
Chris@10 80