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1 | <html> |
2 | <head> | |
3 | <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> | |
4 | <title>Root Finding Without Derivatives</title> | |
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24 | </div> | |
25 | <div class="section"> | |
26 | <div class="titlepage"><div><div><h3 class="title"> | |
27 | <a name="math_toolkit.roots.roots_noderiv"></a><a class="link" href="roots_noderiv.html" title="Root Finding Without Derivatives">Root Finding Without | |
28 | Derivatives</a> | |
29 | </h3></div></div></div> | |
30 | <div class="toc"><dl> | |
31 | <dt><span class="section"><a href="roots_noderiv/bisect.html">Bisection</a></span></dt> | |
32 | <dt><span class="section"><a href="roots_noderiv/bracket_solve.html">Bracket | |
33 | and Solve Root</a></span></dt> | |
34 | <dt><span class="section"><a href="roots_noderiv/TOMS748.html">Algorithm | |
35 | TOMS 748: Alefeld, Potra and Shi: Enclosing zeros of continuous functions</a></span></dt> | |
36 | <dt><span class="section"><a href="roots_noderiv/brent.html">Brent-Decker | |
37 | Algorithm</a></span></dt> | |
38 | <dt><span class="section"><a href="roots_noderiv/root_termination.html">Termination | |
39 | Condition Functors</a></span></dt> | |
40 | <dt><span class="section"><a href="roots_noderiv/implementation.html">Implementation</a></span></dt> | |
41 | </dl></div> | |
42 | <h5> | |
43 | <a name="math_toolkit.roots.roots_noderiv.h0"></a> | |
44 | <span class="phrase"><a name="math_toolkit.roots.roots_noderiv.synopsis"></a></span><a class="link" href="roots_noderiv.html#math_toolkit.roots.roots_noderiv.synopsis">Synopsis</a> | |
45 | </h5> | |
46 | <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">tools</span><span class="special">/</span><span class="identifier">roots</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> | |
47 | </pre> | |
48 | <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">math</span> <span class="special">{</span> | |
49 | <span class="keyword">namespace</span> <span class="identifier">tools</span> <span class="special">{</span> <span class="comment">// Note namespace boost::math::tools.</span> | |
50 | <span class="comment">// Bisection</span> | |
51 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">></span> | |
52 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
53 | <span class="identifier">bisect</span><span class="special">(</span> | |
54 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
55 | <span class="identifier">T</span> <span class="identifier">min</span><span class="special">,</span> | |
56 | <span class="identifier">T</span> <span class="identifier">max</span><span class="special">,</span> | |
57 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
58 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">);</span> | |
59 | ||
60 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">></span> | |
61 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
62 | <span class="identifier">bisect</span><span class="special">(</span> | |
63 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
64 | <span class="identifier">T</span> <span class="identifier">min</span><span class="special">,</span> | |
65 | <span class="identifier">T</span> <span class="identifier">max</span><span class="special">,</span> | |
66 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">);</span> | |
67 | ||
68 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span> | |
69 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
70 | <span class="identifier">bisect</span><span class="special">(</span> | |
71 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
72 | <span class="identifier">T</span> <span class="identifier">min</span><span class="special">,</span> | |
73 | <span class="identifier">T</span> <span class="identifier">max</span><span class="special">,</span> | |
74 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
75 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">,</span> | |
76 | <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span> | |
77 | ||
78 | <span class="comment">// Bracket and Solve Root</span> | |
79 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">></span> | |
80 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
81 | <span class="identifier">bracket_and_solve_root</span><span class="special">(</span> | |
82 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
83 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">guess</span><span class="special">,</span> | |
84 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">factor</span><span class="special">,</span> | |
85 | <span class="keyword">bool</span> <span class="identifier">rising</span><span class="special">,</span> | |
86 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
87 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">);</span> | |
88 | ||
89 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span> | |
90 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
91 | <span class="identifier">bracket_and_solve_root</span><span class="special">(</span> | |
92 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
93 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">guess</span><span class="special">,</span> | |
94 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">factor</span><span class="special">,</span> | |
95 | <span class="keyword">bool</span> <span class="identifier">rising</span><span class="special">,</span> | |
96 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
97 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">,</span> | |
98 | <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span> | |
99 | ||
100 | <span class="comment">// TOMS 748 algorithm</span> | |
101 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">></span> | |
102 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
103 | <span class="identifier">toms748_solve</span><span class="special">(</span> | |
104 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
105 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">a</span><span class="special">,</span> | |
106 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> | |
107 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
108 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">);</span> | |
109 | ||
110 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span> | |
111 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
112 | <span class="identifier">toms748_solve</span><span class="special">(</span> | |
113 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
114 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">a</span><span class="special">,</span> | |
115 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> | |
116 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
117 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">,</span> | |
118 | <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span> | |
119 | ||
120 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">></span> | |
121 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
122 | <span class="identifier">toms748_solve</span><span class="special">(</span> | |
123 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
124 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">a</span><span class="special">,</span> | |
125 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> | |
126 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">fa</span><span class="special">,</span> | |
127 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">fb</span><span class="special">,</span> | |
128 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
129 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">);</span> | |
130 | ||
131 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Tol</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span> | |
132 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">T</span><span class="special">></span> | |
133 | <span class="identifier">toms748_solve</span><span class="special">(</span> | |
134 | <span class="identifier">F</span> <span class="identifier">f</span><span class="special">,</span> | |
135 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">a</span><span class="special">,</span> | |
136 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> | |
137 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">fa</span><span class="special">,</span> | |
138 | <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&</span> <span class="identifier">fb</span><span class="special">,</span> | |
139 | <span class="identifier">Tol</span> <span class="identifier">tol</span><span class="special">,</span> | |
140 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">uintmax_t</span><span class="special">&</span> <span class="identifier">max_iter</span><span class="special">,</span> | |
141 | <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span> | |
142 | ||
143 | <span class="comment">// Termination conditions:</span> | |
144 | <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> | |
145 | <span class="keyword">struct</span> <span class="identifier">eps_tolerance</span><span class="special">;</span> | |
146 | ||
147 | <span class="keyword">struct</span> <span class="identifier">equal_floor</span><span class="special">;</span> | |
148 | <span class="keyword">struct</span> <span class="identifier">equal_ceil</span><span class="special">;</span> | |
149 | <span class="keyword">struct</span> <span class="identifier">equal_nearest_integer</span><span class="special">;</span> | |
150 | ||
151 | <span class="special">}}}</span> <span class="comment">// boost::math::tools namespaces</span> | |
152 | </pre> | |
153 | <h5> | |
154 | <a name="math_toolkit.roots.roots_noderiv.h1"></a> | |
155 | <span class="phrase"><a name="math_toolkit.roots.roots_noderiv.description"></a></span><a class="link" href="roots_noderiv.html#math_toolkit.roots.roots_noderiv.description">Description</a> | |
156 | </h5> | |
157 | <p> | |
158 | These functions solve the root of some function <span class="emphasis"><em>f(x)</em></span> | |
159 | - <span class="emphasis"><em>without the need for any derivatives of <span class="emphasis"><em>f(x)</em></span></em></span>. | |
160 | </p> | |
161 | <p> | |
162 | The <code class="computeroutput"><span class="identifier">bracket_and_solve_root</span></code> | |
163 | functions use <a class="link" href="roots_noderiv/TOMS748.html" title="Algorithm TOMS 748: Alefeld, Potra and Shi: Enclosing zeros of continuous functions">TOMS | |
164 | 748 algorithm</a> by Alefeld, Potra and Shi that is asymptotically the | |
165 | most efficient known, and has been shown to be optimal for a certain classes | |
166 | of smooth functions. Variants with and without <a class="link" href="../../policy.html" title="Chapter 15. Policies: Controlling Precision, Error Handling etc">Policies</a> | |
167 | are provided. | |
168 | </p> | |
169 | <p> | |
170 | Alternatively, <a class="link" href="roots_noderiv/bisect.html" title="Bisection">bisect</a> | |
171 | is a simple <a href="https://en.wikipedia.org/wiki/Bisection" target="_top">bisection</a> | |
172 | routine which can be useful in its own right in some situations, or alternatively | |
173 | for narrowing down the range containing the root, prior to calling a more | |
174 | advanced algorithm. | |
175 | </p> | |
176 | <p> | |
177 | All the algorithms in this section reduce the diameter of the enclosing interval | |
178 | with the same asymptotic efficiency with which they locate the root. This | |
179 | is in contrast to the derivative based methods which may <span class="emphasis"><em>never</em></span> | |
180 | significantly reduce the enclosing interval, even though they rapidly approach | |
181 | the root. This is also in contrast to some other derivative-free methods | |
182 | (for example, Brent's method described at <a href="http://en.wikipedia.org/wiki/Brent%27s_method" target="_top">Brent-Dekker)</a> | |
183 | which only reduces the enclosing interval on the final step. Therefore these | |
184 | methods return a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code> containing the enclosing interval | |
185 | found, and accept a function object specifying the termination condition. | |
186 | </p> | |
187 | <p> | |
188 | Three function objects are provided for ready-made termination conditions: | |
189 | </p> | |
190 | <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> | |
191 | <li class="listitem"> | |
192 | <span class="emphasis"><em>eps_tolerance</em></span> causes termination when the relative | |
193 | error in the enclosing interval is below a certain threshold. | |
194 | </li> | |
195 | <li class="listitem"> | |
196 | <span class="emphasis"><em>equal_floor</em></span> and <span class="emphasis"><em>equal_ceil</em></span> | |
197 | are useful for certain statistical applications where the result is known | |
198 | to be an integer. | |
199 | </li> | |
200 | <li class="listitem"> | |
201 | Other user-defined termination conditions are likely to be used only | |
202 | rarely, but may be useful in some specific circumstances. | |
203 | </li> | |
204 | </ul></div> | |
205 | </div> | |
206 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
207 | <td align="left"></td> | |
208 | <td align="right"><div class="copyright-footer">Copyright © 2006-2010, 2012-2014 Nikhar Agrawal, | |
209 | Anton Bikineev, Paul A. Bristow, Marco Guazzone, Christopher Kormanyos, Hubert | |
210 | Holin, Bruno Lalande, John Maddock, Jeremy Murphy, Johan Råde, Gautam Sewani, | |
211 | Benjamin Sobotta, Thijs van den Berg, Daryle Walker and Xiaogang Zhang<p> | |
212 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
213 | file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) | |
214 | </p> | |
215 | </div></td> | |
216 | </tr></table> | |
217 | <hr> | |
218 | <div class="spirit-nav"> | |
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