Mercurial > hg > batch-feature-extraction-tool
diff Lib/fftw-3.2.1/doc/html/.svn/text-base/Dynamic-Arrays-in-C_002dThe-Wrong-Way.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/Dynamic-Arrays-in-C_002dThe-Wrong-Way.html.svn-base Wed May 04 11:02:59 2016 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,93 +0,0 @@ -<html lang="en"> -<head> -<title>Dynamic Arrays in C-The Wrong Way - 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="Multi_002ddimensional-Array-Format.html#Multi_002ddimensional-Array-Format" title="Multi-dimensional Array Format"> -<link rel="prev" href="Dynamic-Arrays-in-C.html#Dynamic-Arrays-in-C" title="Dynamic Arrays in C"> -<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="Dynamic-Arrays-in-C-The-Wrong-Way"></a> -<a name="Dynamic-Arrays-in-C_002dThe-Wrong-Way"></a> -Previous: <a rel="previous" accesskey="p" href="Dynamic-Arrays-in-C.html#Dynamic-Arrays-in-C">Dynamic Arrays in C</a>, -Up: <a rel="up" accesskey="u" href="Multi_002ddimensional-Array-Format.html#Multi_002ddimensional-Array-Format">Multi-dimensional Array Format</a> -<hr> -</div> - -<h4 class="subsection">3.2.5 Dynamic Arrays in C—The Wrong Way</h4> - -<p>A different method for allocating multi-dimensional arrays in C is -often suggested that is incompatible with FFTW: <em>using it will -cause FFTW to die a painful death</em>. We discuss the technique here, -however, because it is so commonly known and used. This method is to -create arrays of pointers of arrays of pointers of <small class="dots">...</small>etcetera. -For example, the analogue in this method to the example above is: - -<pre class="example"> int i,j; - fftw_complex ***a_bad_array; /* <span class="roman">another way to make a 5x12x27 array</span> */ - - a_bad_array = (fftw_complex ***) malloc(5 * sizeof(fftw_complex **)); - for (i = 0; i < 5; ++i) { - a_bad_array[i] = - (fftw_complex **) malloc(12 * sizeof(fftw_complex *)); - for (j = 0; j < 12; ++j) - a_bad_array[i][j] = - (fftw_complex *) malloc(27 * sizeof(fftw_complex)); - } -</pre> - <p>As you can see, this sort of array is inconvenient to allocate (and -deallocate). On the other hand, it has the advantage that the -(i,j,k)-th element can be referenced simply by -<code>a_bad_array[i][j][k]</code>. - - <p>If you like this technique and want to maximize convenience in accessing -the array, but still want to pass the array to FFTW, you can use a -hybrid method. Allocate the array as one contiguous block, but also -declare an array of arrays of pointers that point to appropriate places -in the block. That sort of trick is beyond the scope of this -documentation; for more information on multi-dimensional arrays in C, -see the <code>comp.lang.c</code> -<a href="http://www.eskimo.com/~scs/C-faq/s6.html">FAQ</a>. - -<!-- --> -</body></html> -