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26 <div class="titlepage"><div><div><h3 class="title">
27 <a name="math_toolkit.ellint.ellint_3"></a><a class="link" href="ellint_3.html" title="Elliptic Integrals of the Third Kind - Legendre Form">Elliptic Integrals of the
28 Third Kind - Legendre Form</a>
29 </h3></div></div></div>
31 <a name="math_toolkit.ellint.ellint_3.h0"></a>
32 <span class="phrase"><a name="math_toolkit.ellint.ellint_3.synopsis"></a></span><a class="link" href="ellint_3.html#math_toolkit.ellint.ellint_3.synopsis">Synopsis</a>
34 <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">special_functions</span><span class="special">/</span><span class="identifier">ellint_3</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
36 <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>
38 <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T3</span><span class="special">></span>
39 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">T3</span> <span class="identifier">phi</span><span class="special">);</span>
41 <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T3</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span>
42 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">T3</span> <span class="identifier">phi</span><span class="special">,</span> <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span>
44 <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">></span>
45 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">);</span>
47 <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span>
48 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">,</span> <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span>
50 <span class="special">}}</span> <span class="comment">// namespaces</span>
53 <a name="math_toolkit.ellint.ellint_3.h1"></a>
54 <span class="phrase"><a name="math_toolkit.ellint.ellint_3.description"></a></span><a class="link" href="ellint_3.html#math_toolkit.ellint.ellint_3.description">Description</a>
57 These two functions evaluate the incomplete elliptic integral of the third
58 kind <span class="emphasis"><em>Π(n, φ, k)</em></span> and its complete counterpart <span class="emphasis"><em>Π(n,
59 k) = E(n, π/2, k)</em></span>.
61 <div class="blockquote"><blockquote class="blockquote"><p>
62 <span class="inlinemediaobject"><img src="../../../graphs/ellint_3.svg" align="middle"></span>
64 </p></blockquote></div>
66 The return type of these functions is computed using the <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>result
67 type calculation rules</em></span></a> when the arguments are of different
68 types: when they are the same type then the result is the same type as the
71 <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T3</span><span class="special">></span>
72 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">T3</span> <span class="identifier">phi</span><span class="special">);</span>
74 <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T3</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span>
75 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">T3</span> <span class="identifier">phi</span><span class="special">,</span> <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span>
78 Returns the incomplete elliptic integral of the third kind <span class="emphasis"><em>Π(n,
79 φ, k)</em></span>:
81 <div class="blockquote"><blockquote class="blockquote"><p>
82 <span class="inlinemediaobject"><img src="../../../equations/ellint4.svg"></span>
84 </p></blockquote></div>
86 Requires <span class="emphasis"><em>k<sup>2</sup>sin<sup>2</sup>(phi) < 1</em></span> and <span class="emphasis"><em>n < 1/sin<sup>2</sup>(φ)</em></span>,
87 otherwise returns the result of <a class="link" href="../error_handling.html#math_toolkit.error_handling.domain_error">domain_error</a>
88 (outside this range the result would be complex).
91 The final <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a> argument is optional and can
92 be used to control the behaviour of the function: how it handles errors,
93 what level of precision to use etc. Refer to the <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">policy
94 documentation for more details</a>.
96 <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">></span>
97 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">);</span>
99 <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T2</span><span class="special">,</span> <span class="keyword">class</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">></span>
100 <a class="link" href="../result_type.html" title="Calculation of the Type of the Result"><span class="emphasis"><em>calculated-result-type</em></span></a> <span class="identifier">ellint_3</span><span class="special">(</span><span class="identifier">T1</span> <span class="identifier">k</span><span class="special">,</span> <span class="identifier">T2</span> <span class="identifier">n</span><span class="special">,</span> <span class="keyword">const</span> <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a><span class="special">&);</span>
103 Returns the complete elliptic integral of the first kind <span class="emphasis"><em>Π(n, k)</em></span>:
105 <div class="blockquote"><blockquote class="blockquote"><p>
106 <span class="inlinemediaobject"><img src="../../../equations/ellint8.svg"></span>
108 </p></blockquote></div>
110 Requires <span class="emphasis"><em>|k| < 1</em></span> and <span class="emphasis"><em>n < 1</em></span>,
111 otherwise returns the result of <a class="link" href="../error_handling.html#math_toolkit.error_handling.domain_error">domain_error</a>
112 (outside this range the result would be complex).
115 The final <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">Policy</a> argument is optional and can
116 be used to control the behaviour of the function: how it handles errors,
117 what level of precision to use etc. Refer to the <a class="link" href="../../policy.html" title="Chapter 20. Policies: Controlling Precision, Error Handling etc">policy
118 documentation for more details</a>.
121 <a name="math_toolkit.ellint.ellint_3.h2"></a>
122 <span class="phrase"><a name="math_toolkit.ellint.ellint_3.accuracy"></a></span><a class="link" href="ellint_3.html#math_toolkit.ellint.ellint_3.accuracy">Accuracy</a>
125 These functions are computed using only basic arithmetic operations, so there
126 isn't much variation in accuracy over differing platforms. Note that only
127 results for the widest floating point type on the system are given as narrower
128 types have <a class="link" href="../relative_error.html#math_toolkit.relative_error.zero_error">effectively
129 zero error</a>. All values are relative errors in units of epsilon.
132 <a name="math_toolkit.ellint.ellint_3.table_ellint_3"></a><p class="title"><b>Table 8.65. Error rates for ellint_3</b></p>
133 <div class="table-contents"><table class="table" summary="Error rates for ellint_3">
146 GNU C++ version 7.1.0<br> linux<br> long double
151 GNU C++ version 7.1.0<br> linux<br> double
156 Sun compiler version 0x5150<br> Sun Solaris<br> long double
161 Microsoft Visual C++ version 14.1<br> Win32<br> double
169 Elliptic Integral PI: Mathworld Data
174 <span class="blue">Max = 475ε (Mean = 86.3ε)</span><br> <br>
175 (<span class="emphasis"><em><cmath>:</em></span> <span class="red">Max = +INFε (Mean
176 = +INFε) <a class="link" href="../logs_and_tables/logs.html#errors_GNU_C_version_7_1_0_linux_long_double_ellint_3__cmath__Elliptic_Integral_PI_Mathworld_Data">And
177 other failures.</a>)</span>
182 <span class="blue">Max = 0ε (Mean = 0ε)</span><br> <br> (<span class="emphasis"><em>GSL
183 2.1:</em></span> Max = 1.48e+05ε (Mean = 2.54e+04ε) <a class="link" href="../logs_and_tables/logs.html#errors_GNU_C_version_7_1_0_linux_double_ellint_3_GSL_2_1_Elliptic_Integral_PI_Mathworld_Data">And
189 <span class="blue">Max = 475ε (Mean = 86.3ε)</span>
194 <span class="blue">Max = 565ε (Mean = 102ε)</span>
201 Elliptic Integral PI: Random Data
206 <span class="blue">Max = 4.54ε (Mean = 0.895ε)</span><br> <br>
207 (<span class="emphasis"><em><cmath>:</em></span> <span class="red">Max = 3.37e+20ε (Mean
208 = 3.47e+19ε) <a class="link" href="../logs_and_tables/logs.html#errors_GNU_C_version_7_1_0_linux_long_double_ellint_3__cmath__Elliptic_Integral_PI_Random_Data">And
209 other failures.</a>)</span>
214 <span class="blue">Max = 0ε (Mean = 0ε)</span><br> <br> (<span class="emphasis"><em>GSL
215 2.1:</em></span> Max = 633ε (Mean = 50.1ε))
220 <span class="blue">Max = 4.49ε (Mean = 0.885ε)</span>
225 <span class="blue">Max = 8.33ε (Mean = 0.971ε)</span>
232 Elliptic Integral PI: Large Random Data
237 <span class="blue">Max = 3.7ε (Mean = 0.893ε)</span><br> <br>
238 (<span class="emphasis"><em><cmath>:</em></span> <span class="red">Max = 2.52e+18ε (Mean
239 = 4.83e+17ε) <a class="link" href="../logs_and_tables/logs.html#errors_GNU_C_version_7_1_0_linux_long_double_ellint_3__cmath__Elliptic_Integral_PI_Large_Random_Data">And
240 other failures.</a>)</span>
245 <span class="blue">Max = 0.557ε (Mean = 0.0389ε)</span><br>
246 <br> (<span class="emphasis"><em>GSL 2.1:</em></span> Max = 40.1ε (Mean = 7.77ε))
251 <span class="blue">Max = 3.7ε (Mean = 0.892ε)</span>
256 <span class="blue">Max = 2.86ε (Mean = 0.944ε)</span>
263 <br class="table-break"><h5>
264 <a name="math_toolkit.ellint.ellint_3.h3"></a>
265 <span class="phrase"><a name="math_toolkit.ellint.ellint_3.testing"></a></span><a class="link" href="ellint_3.html#math_toolkit.ellint.ellint_3.testing">Testing</a>
268 The tests use a mixture of spot test values calculated using the online calculator
269 at <a href="http://functions.wolfram.com" target="_top">functions.wolfram.com</a>,
270 and random test data generated using NTL::RR at 1000-bit precision and this
274 <a name="math_toolkit.ellint.ellint_3.h4"></a>
275 <span class="phrase"><a name="math_toolkit.ellint.ellint_3.implementation"></a></span><a class="link" href="ellint_3.html#math_toolkit.ellint.ellint_3.implementation">Implementation</a>
278 The implementation for Π(n, φ, k) first siphons off the special cases:
280 <div class="blockquote"><blockquote class="blockquote"><p>
281 <span class="serif_italic"><span class="emphasis"><em>Π(0, φ, k) = F(φ, k)</em></span></span>
282 </p></blockquote></div>
283 <div class="blockquote"><blockquote class="blockquote"><p>
284 <span class="serif_italic"><span class="emphasis"><em>Π(n, π/2, k) = Π(n, k)</em></span></span>
285 </p></blockquote></div>
289 <div class="blockquote"><blockquote class="blockquote"><p>
290 <span class="inlinemediaobject"><img src="../../../equations/ellint23.svg"></span>
292 </p></blockquote></div>
294 Then if n < 0 the relations (A&S 17.7.15/16):
296 <div class="blockquote"><blockquote class="blockquote"><p>
297 <span class="inlinemediaobject"><img src="../../../equations/ellint24.svg"></span>
299 </p></blockquote></div>
301 are used to shift <span class="emphasis"><em>n</em></span> to the range [0, 1].
306 <div class="blockquote"><blockquote class="blockquote"><p>
307 <span class="serif_italic"><span class="emphasis"><em>Π(n, -φ, k) = -Π(n, φ, k)</em></span></span>
308 </p></blockquote></div>
309 <div class="blockquote"><blockquote class="blockquote"><p>
310 <span class="serif_italic"><span class="emphasis"><em>Π(n, φ+mπ, k) = Π(n, φ, k) + 2mΠ(n, k)
311 ; n <= 1</em></span></span>
312 </p></blockquote></div>
313 <div class="blockquote"><blockquote class="blockquote"><p>
314 <span class="serif_italic"><span class="emphasis"><em>Π(n, φ+mπ, k) = Π(n, φ, k) ; n > 1</em></span>
315        
316 <a href="#ftn.math_toolkit.ellint.ellint_3.f0" class="footnote" name="math_toolkit.ellint.ellint_3.f0"><sup class="footnote">[1]</sup></a></span>
317 </p></blockquote></div>
319 are used to move φ to the range [0, π/2].
322 The functions are then implemented in terms of Carlson's integrals using
325 <div class="blockquote"><blockquote class="blockquote"><p>
326 <span class="inlinemediaobject"><img src="../../../equations/ellint25.svg"></span>
328 </p></blockquote></div>
332 <div class="blockquote"><blockquote class="blockquote"><p>
333 <span class="inlinemediaobject"><img src="../../../equations/ellint26.svg"></span>
335 </p></blockquote></div>
336 <div class="footnotes">
337 <br><hr style="width:100; text-align:left;margin-left: 0">
338 <div id="ftn.math_toolkit.ellint.ellint_3.f0" class="footnote"><p><a href="#math_toolkit.ellint.ellint_3.f0" class="para"><sup class="para">[1] </sup></a>
339 I haven't been able to find a literature reference for this relation,
340 but it appears to be the convention used by Mathematica. Intuitively
341 the first <span class="emphasis"><em>2 * m * Π(n, k)</em></span> terms cancel out as the
342 derivative alternates between +∞ and -∞.
346 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
347 <td align="left"></td>
348 <td align="right"><div class="copyright-footer">Copyright © 2006-2019 Nikhar
349 Agrawal, Anton Bikineev, Paul A. Bristow, Marco Guazzone, Christopher Kormanyos,
350 Hubert Holin, Bruno Lalande, John Maddock, Jeremy Murphy, Matthew Pulver, Johan
351 Råde, Gautam Sewani, Benjamin Sobotta, Nicholas Thompson, Thijs van den Berg,
352 Daryle Walker and Xiaogang Zhang<p>
353 Distributed under the Boost Software License, Version 1.0. (See accompanying
354 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>)
359 <div class="spirit-nav">
360 <a accesskey="p" href="ellint_2.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ellint.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="ellint_d.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>