Mercurial > hg > batch-feature-extraction-tool
diff Lib/fftw-3.2.1/doc/html/.svn/text-base/Complex-numbers.html.svn-base @ 15:585caf503ef5 tip
Tidy up for ROLI
| author | Geogaddi\David <d.m.ronan@qmul.ac.uk> |
|---|---|
| date | Tue, 17 May 2016 18:50:19 +0100 |
| parents | 636c989477e7 |
| children |
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--- a/Lib/fftw-3.2.1/doc/html/.svn/text-base/Complex-numbers.html.svn-base Wed May 04 11:02:59 2016 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,95 +0,0 @@ -<html lang="en"> -<head> -<title>Complex numbers - FFTW 3.2.1</title> -<meta http-equiv="Content-Type" content="text/html"> -<meta name="description" content="FFTW 3.2.1"> -<meta name="generator" content="makeinfo 4.8"> -<link title="Top" rel="start" href="index.html#Top"> -<link rel="up" href="Data-Types-and-Files.html#Data-Types-and-Files" title="Data Types and Files"> -<link rel="prev" href="Data-Types-and-Files.html#Data-Types-and-Files" title="Data Types and Files"> -<link rel="next" href="Precision.html#Precision" title="Precision"> -<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> -<!-- -This manual is for FFTW -(version 3.2.1, 5 February 2009). - -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. - --> -<meta http-equiv="Content-Style-Type" content="text/css"> -<style type="text/css"><!-- - pre.display { font-family:inherit } - pre.format { font-family:inherit } - pre.smalldisplay { font-family:inherit; font-size:smaller } - pre.smallformat { font-family:inherit; font-size:smaller } - pre.smallexample { font-size:smaller } - pre.smalllisp { font-size:smaller } - span.sc { font-variant:small-caps } - span.roman { font-family:serif; font-weight:normal; } - span.sansserif { font-family:sans-serif; font-weight:normal; } ---></style> -</head> -<body> -<div class="node"> -<p> -<a name="Complex-numbers"></a> -Next: <a rel="next" accesskey="n" href="Precision.html#Precision">Precision</a>, -Previous: <a rel="previous" accesskey="p" href="Data-Types-and-Files.html#Data-Types-and-Files">Data Types and Files</a>, -Up: <a rel="up" accesskey="u" href="Data-Types-and-Files.html#Data-Types-and-Files">Data Types and Files</a> -<hr> -</div> - -<h4 class="subsection">4.1.1 Complex numbers</h4> - -<p>The default FFTW interface uses <code>double</code> precision for all -floating-point numbers, and defines a <code>fftw_complex</code> type to hold -complex numbers as: - -<pre class="example"> typedef double fftw_complex[2]; -</pre> - <p><a name="index-fftw_005fcomplex-136"></a> -Here, the <code>[0]</code> element holds the real part and the <code>[1]</code> -element holds the imaginary part. - - <p>Alternatively, if you have a C compiler (such as <code>gcc</code>) that -supports the C99 revision of the ANSI C standard, you can use C's new -native complex type (which is binary-compatible with the typedef above). -In particular, if you <code>#include <complex.h></code> <em>before</em> -<code><fftw3.h></code>, then <code>fftw_complex</code> is defined to be the native -complex type and you can manipulate it with ordinary arithmetic -(e.g. <code>x = y * (3+4*I)</code>, where <code>x</code> and <code>y</code> are -<code>fftw_complex</code> and <code>I</code> is the standard symbol for the -imaginary unit); -<a name="index-C99-137"></a> -C++ has its own <code>complex<T></code> template class, defined in the -standard <code><complex></code> header file. Reportedly, the C++ standards -committee has recently agreed to mandate that the storage format used -for this type be binary-compatible with the C99 type, i.e. an array -<code>T[2]</code> with consecutive real <code>[0]</code> and imaginary <code>[1]</code> -parts. (See report -<a href="http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2002/1388.pdf">WG21/N1388</a>.) Although not part of the official standard as of this -writing, the proposal stated that: “This solution has been tested with -all current major implementations of the standard library and shown to -be working.” To the extent that this is true, if you have a variable -<code>complex<double> *x</code>, you can pass it directly to FFTW via -<code>reinterpret_cast<fftw_complex*>(x)</code>. -<a name="index-C_002b_002b-138"></a><a name="index-portability-139"></a> -<!-- =========> --> - - </body></html> -