dither.cpp
Go to the documentation of this file.
1 /*********************************************************************
2  * Software License Agreement (BSD License)
3  *
4  * Copyright (c) 2009, Willow Garage, Inc.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * * Redistributions of source code must retain the above copyright
12  * notice, this list of conditions and the following disclaimer.
13  * * Redistributions in binary form must reproduce the above
14  * copyright notice, this list of conditions and the following
15  * disclaimer in the documentation and/or other materials provided
16  * with the distribution.
17  * * Neither the name of the Willow Garage nor the names of its
18  * contributors may be used to endorse or promote products derived
19  * from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
29  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
31  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32  * POSSIBILITY OF SUCH DAMAGE.
33  *********************************************************************/
34 
35 // Original version: Kevin Watts <watts@willowgarage.com>
36 
37 #include <control_toolbox/dither.h>
38 
39 #include <random>
40 
41 namespace control_toolbox {
42 
43 Dither::Dither() : amplitude_(0), has_saved_value_(false)
44 {
45 
46 }
47 
48 Dither::~Dither()
49 {
50 }
51 
52 double Dither::update()
53 {
54  if (has_saved_value_)
55  {
56  has_saved_value_ = false;
57  return saved_value_;
58  }
59 
60  // Generates gaussian random noise using the polar method.
61  double v1, v2, r;
62  // uniform distribution on the interval [-1.0, 1.0]
63  std::uniform_real_distribution<double> distribution(-1.0, std::nextafter(1.0, std::numeric_limits<double>::max()));
64  for (int i = 0; i < 100; ++i)
65  {
66  v1 = distribution(generator_);
67  v2 = distribution(generator_);
68  r = v1*v1 + v2*v2;
69  if (r <= 1.0)
70  break;
71  }
72  if (r > 1.0)
73  r = 1.0;
74 
75  double f = sqrt(-2.0 * log(r) / r);
76  double current = amplitude_ * f * v1;
77  saved_value_ = amplitude_ * f * v2;
78  has_saved_value_ = true;
79 
80  return current;
81 }
82 
83 }
control_toolbox::Dither::Dither
Dither()
Definition: dither.cpp:75
f
f
dither.h
control_toolbox
Definition: dither.h:46


control_toolbox
Author(s): Melonee Wise, Sachin Chitta, John Hsu
autogenerated on Wed May 11 2022 02:09:46