File: DWT-Examples.html

package info (click to toggle)
gsl-ref-html 2.3-1
  • links: PTS
  • area: non-free
  • in suites: bullseye, buster, sid
  • size: 6,876 kB
  • ctags: 4,574
  • sloc: makefile: 35
file content (148 lines) | stat: -rw-r--r-- 5,277 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 The GSL Team.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "GNU General Public License" and "Free Software
Needs Free Documentation", the Front-Cover text being "A GNU Manual",
and with the Back-Cover Text being (a) (see below). A copy of the
license is included in the section entitled "GNU Free Documentation
License".

(a) The Back-Cover Text is: "You have the freedom to copy and modify this
GNU Manual." -->
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
<head>
<title>GNU Scientific Library &ndash; Reference Manual: DWT Examples</title>

<meta name="description" content="GNU Scientific Library &ndash; Reference Manual: DWT Examples">
<meta name="keywords" content="GNU Scientific Library &ndash; Reference Manual: DWT Examples">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Function-Index.html#Function-Index" rel="index" title="Function Index">
<link href="Wavelet-Transforms.html#Wavelet-Transforms" rel="up" title="Wavelet Transforms">
<link href="DWT-References.html#DWT-References" rel="next" title="DWT References">
<link href="DWT-in-two-dimension.html#DWT-in-two-dimension" rel="previous" title="DWT in two dimension">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {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}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="DWT-Examples"></a>
<div class="header">
<p>
Next: <a href="DWT-References.html#DWT-References" accesskey="n" rel="next">DWT References</a>, Previous: <a href="DWT-Transform-Functions.html#DWT-Transform-Functions" accesskey="p" rel="previous">DWT Transform Functions</a>, Up: <a href="Wavelet-Transforms.html#Wavelet-Transforms" accesskey="u" rel="up">Wavelet Transforms</a> &nbsp; [<a href="Function-Index.html#Function-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Examples-23"></a>
<h3 class="section">32.4 Examples</h3>

<p>The following program demonstrates the use of the one-dimensional
wavelet transform functions.  It computes an approximation to an input
signal (of length 256) using the 20 largest components of the wavelet
transform, while setting the others to zero.
</p>
<div class="example">
<pre class="verbatim">#include &lt;stdio.h&gt;
#include &lt;math.h&gt;
#include &lt;gsl/gsl_sort.h&gt;
#include &lt;gsl/gsl_wavelet.h&gt;

int
main (int argc, char **argv)
{
  (void)(argc); /* avoid unused parameter warning */
  int i, n = 256, nc = 20;
  double *data = malloc (n * sizeof (double));
  double *abscoeff = malloc (n * sizeof (double));
  size_t *p = malloc (n * sizeof (size_t));

  FILE * f;
  gsl_wavelet *w;
  gsl_wavelet_workspace *work;

  w = gsl_wavelet_alloc (gsl_wavelet_daubechies, 4);
  work = gsl_wavelet_workspace_alloc (n);

  f = fopen (argv[1], &quot;r&quot;);
  for (i = 0; i &lt; n; i++)
    {
      fscanf (f, &quot;%lg&quot;, &amp;data[i]);
    }
  fclose (f);

  gsl_wavelet_transform_forward (w, data, 1, n, work);

  for (i = 0; i &lt; n; i++)
    {
      abscoeff[i] = fabs (data[i]);
    }
  
  gsl_sort_index (p, abscoeff, 1, n);
  
  for (i = 0; (i + nc) &lt; n; i++)
    data[p[i]] = 0;
  
  gsl_wavelet_transform_inverse (w, data, 1, n, work);
  
  for (i = 0; i &lt; n; i++)
    {
      printf (&quot;%g\n&quot;, data[i]);
    }
  
  gsl_wavelet_free (w);
  gsl_wavelet_workspace_free (work);

  free (data);
  free (abscoeff);
  free (p);
  return 0;
}
</pre></div>

<p>The output can be used with the <small>GNU</small> plotutils <code>graph</code> program,
</p>
<div class="example">
<pre class="example">$ ./a.out ecg.dat &gt; dwt.txt
$ graph -T ps -x 0 256 32 -h 0.3 -a dwt.txt &gt; dwt.ps
</pre></div>





</body>
</html>