[CI SKIP] Added missing example file and more index entries

doc/index.idx

@@ -60,7 +60,7 @@ DCDFLIB
 
 feedback
 
-bugs \<bug\w*\>
+bug \<bug\w*\>
 
 GIT \<GIT\w*\>
 

doc/overview/structure.qbk

@@ -51,28 +51,28 @@ This documentation aims to use of the following naming and formatting convention
 * Names that refer to ['concepts] in the generic programming sense 
 (like template parameter names) are specified in CamelCase.
 
-
 [endsect] [/section:conventions Document Conventions]
 
 [section:hints Other Hints and tips]
 
-* If you have a feature request,
-or if it appears that the implementation is in error,
-please search first in the [@https://svn.boost.org/trac/boost/ Boost Trac].
-
-* [@https://svn.boost.org/trac/boost/ Trac] entries may indicate that
-updates or corrections that solve your problem are in 
-[@http://svn.boost.org/svn/boost/trunk Boost-trunk]
-where changes are being assembled and tested ready for the next release.
+* Historial records of issues are at [@https://svn.boost.org/trac/boost/ Boost Trac].
+* Always ensure that you are using the  [@https://www.boost.org/users/download/#live current release version].
+* The current documentation for the release version is [@https://www.boost.org/doc/libs/release/libs/math/doc/html/index.html here].
+* The current documentation for the version being developed is [@https://www.boost.org/doc/libs/develop/libs/math/doc/html/index.html here].
+* See [@https://github.com/boostorg/math develop branch(es)] where changes are being assembled and tested ready for the next release.[br]
 You may, at your own risk, download new versions from there.
-
+* If you have a new feature request, raise a new [@https://github.com/boostorg/math/issues Boost.Math issue],
+* If it appears that the implementation is in error,
+please search first at [@https://github.com/boostorg/math/issues Boost.Math issues].
+Entries may indicate that updates or corrections that solve your problem are in 
+[@https://github.com/boostorg/math Boost.Math on Github].
 * If you do not understand why things work the way they do, see the ['rationale] section.
+* If you do not find satisfaction for your idea/feature/complaint,
+please reach the author(s) preferably through the [@boost@lists.boost.org Boost development list],
+or raise a new [@https://github.com/boostorg/math/issues Boost.Math issue],
+or email the author(s) direct.
 
-* If you do not find your idea/feature/complaint,
-please reach the author preferably through the Boost
-development list, or email the author(s) direct.
-
-[h5 Admonishments]
+[h5:admonishments Admonishments]
 
 [note In addition, notes such as this one specify non-essential information that
 provides additional background or rationale.]
@@ -83,8 +83,7 @@ provides additional background or rationale.]
 Failure to follow suggestions in these blocks will probably result in undesired behavior.
 Read all of these you find.]
 
-[warning Failure to heed this will lead to incorrect,
-and very likely undesired, results.]
+[warning Failure to heed this will lead to incorrect, and very likely undesired, results.]
 
 [endsect] [/section:hints Other Hints and tips]
 
@@ -100,12 +99,11 @@ and very likely undesired, results.]
    as the RealType (and short `typedef` names of distributions are 
    reserved for this type where possible), a few will use `float` or 
    `long double`, but it is also possible to use higher precision types 
-   like __NTL_RR, __GMP, __MPFR
+   like __NTL_RR, __GMP, __MPFR, __multiprecision like cpp_bin_float_50
 that conform to the requirements specified by real_concept.]]
 
 [[\/constants\/]
-   [Templated definition of some highly accurate math 
-   constants (in constants.hpp).]]
+   [Templated definition of some highly accurate math constants ([@https://github.com/boostorg/math/blob/develop/include/boost/math/constants/constants.hpp constants.hpp]).]]
   
 [[\/distributions\/]
    [Distributions used in mathematics and, especially, statistics: 

doc/sf/factorials.qbk

@@ -183,13 +183,13 @@ generated by functions.wolfram.com.
 The double factorial is implemented in terms of the factorial and gamma
 functions using the relations:
 
-[:(2n)!! = 2[super n ] * n!]
+[:['(2n)!! = 2[super n ] * n!]]
 
-[:(2n+1)!! = (2n+1)! / (2[super n ] n!)]
+[:['(2n+1)!! = (2n+1)! / (2[super n ] n!)]]
 
 and
 
-[:(2n-1)!! = [Gamma]((2n+1)/2) * 2[super n ] / sqrt(pi)]
+[:['(2n-1)!! = [Gamma]((2n+1)/2) * 2[super n ] / sqrt(pi)]]
 
 [endsect] [/section:sf_double_factorial Double Factorial]
 
@@ -211,11 +211,11 @@ and
 
 Returns the rising factorial of /x/ and /i/:
 
-[:rising_factorial(x, i) = [Gamma](x + i) / [Gamma](x)]
+[:['rising_factorial(x, i) = [Gamma](x + i) / [Gamma](x)]]
 
 or
 
-[:rising_factorial(x, i) = x(x+1)(x+2)(x+3)...(x+i-1)]
+[:['rising_factorial(x, i) = x(x+1)(x+2)(x+3)...(x+i-1)]]
                           
 Note that both /x/ and /i/ can be negative as well as positive.
 
@@ -240,7 +240,7 @@ by functions.wolfram.com.
 
 [h4 Implementation]
 
-Rising and falling factorials are implemented as ratios of gamma functions
+Rising and [' factorials are implemented as ratios of gamma functions
 using __tgamma_delta_ratio.  Optimisations for
 small integer arguments are handled internally by that function.
 
@@ -264,7 +264,7 @@ small integer arguments are handled internally by that function.
 
 Returns the falling factorial of /x/ and /i/:
 
-[:falling_factorial(x, i) = x(x-1)(x-2)(x-3)...(x-i+1)]
+[:['falling_factorial(x, i) = x(x-1)(x-2)(x-3)...(x-i+1)]]
    
 Note that this function is only defined for positive /i/, hence the
 `unsigned` second argument.  Argument /x/ can be either positive or
@@ -353,15 +353,15 @@ generated by functions.wolfram.com.
 Binomial coefficients are calculated using table lookup of factorials
 where possible using:
 
-[:[sub n]C[sub k] = n! / (k!(n-k)!)]
+[:['[sub n]C[sub k] = n! / (k!(n-k)!)]]
 
 Otherwise it is implemented in terms of the beta function using the relations:
 
-[:[sub n]C[sub k] = 1 / (k * __beta(k, n-k+1))]
+[:['[sub n]C[sub k] = 1 / (k * __beta(k, n-k+1))]]
 
 and
 
-[:[sub n]C[sub k] = 1 / ((n-k) * __beta(k+1, n-k))]
+[:['[sub n]C[sub k] = 1 / ((n-k) * __beta(k+1, n-k))]]
 
 [endsect] [/section:sf_binomial Binomial Coefficients]
 

example/jacobi_zeta_example.cpp

@@ -0,0 +1,104 @@
+// Copyright Paul A. Bristow, 2019
+
+// Use, modification and distribution are subject to the
+// Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+/*! \title  Simple example of computation of the Jacobi Zeta function using Boost.Math,
+and also using corresponding WolframAlpha commands.
+*/
+
+#ifdef BOOST_NO_CXX11_NUMERIC_LIMITS
+#  error "This example requires a C++ compiler that supports C++11 numeric_limits. Try C++11 or later."
+#endif
+
+#include <boost/math/special_functions/jacobi_zeta.hpp> // For jacobi_zeta function.
+#include <boost/multiprecision/cpp_bin_float.hpp> // For cpp_bin_float_50.
+
+#include <iostream>
+#include <limits>
+#include <iostream>
+#include <exception>
+
+int main()
+{
+  try
+  {
+    std::cout.precision(std::numeric_limits<double>::max_digits10); // Show all potentially significant digits.
+    std::cout.setf(std::ios_base::showpoint); // Include any significant trailing zeros.
+
+    using boost::math::jacobi_zeta; // jacobi_zeta(T1 k, T2 phi) |k| <=1, k = sqrt(m)
+    using boost::multiprecision::cpp_bin_float_50;
+
+    // Wolfram Mathworld function JacobiZeta[phi, m] where m = k^2
+    // JacobiZeta[phi,m] gives the Jacobi zeta function Z(phi | m)
+
+    // If phi = 2, and elliptic modulus k = 0.9 so m = 0.9 * 0.9 = 0.81
+
+    // https://reference.wolfram.com/language/ref/JacobiZeta.html // Function information.
+    // A simple computation using phi = 2. and m = 0.9 * 0.9
+    // JacobiZeta[2, 0.9 * 0.9]
+    // https://www.wolframalpha.com/input/?i=JacobiZeta%5B2,+0.9+*+0.9%5D
+    // -0.248584...
+    // To get the expected 17 decimal digits precision for a 64-bit double type,
+    // we need to ask thus:
+    // N[JacobiZeta[2, 0.9 * 0.9],17]
+    // https://www.wolframalpha.com/input/?i=N%5BJacobiZeta%5B2,+0.9+*+0.9%5D,17%5D
+
+    double k = 0.9;
+    double m = k * k;
+    double phi = 2.;
+
+    std::cout << "m = k^2 = " << m << std::endl;  // m = k^2 =  0.81000000000000005
+    std::cout << "jacobi_zeta(" << k << ", " << phi << " )  = " << jacobi_zeta(k, phi) << std::endl;
+    // jacobi_zeta(0.90000000000000002, 2.0000000000000000 )  =
+    //  -0.24858442708494899  Boost.Math
+    //  -0.24858442708494893  Wolfram
+    // that agree within the expected precision of 17 decimal digits for 64-bit type double.
+
+    // We can also easily get a higher precision too:
+    // For example, to get 50 decimal digit precision using WolframAlpha:
+    // N[JacobiZeta[2, 0.9 * 0.9],50]
+    // https://www.wolframalpha.com/input/?i=N%5BJacobiZeta%5B2,+0.9+*+0.9%5D,50%5D
+    // -0.24858442708494893408462856109734087389683955309853
+
+    // Using Boost.Multiprecision we can do them same almost as easily.
+
+    // To check that we are not losing precision, we show all the significant digits of the arguments ad result:
+    std::cout.precision(std::numeric_limits<cpp_bin_float_50>::digits10); // Show all significant digits.
+
+    // We can force the computation to use 50 decimal digit precision thus:
+    cpp_bin_float_50 k50("0.9");
+    cpp_bin_float_50 phi50("2.");
+
+    std::cout << "jacobi_zeta(" << k50 << ", " << phi50 << " )  = " << jacobi_zeta(k50, phi50) << std::endl;
+    // jacobi_zeta(0.90000000000000000000000000000000000000000000000000,
+    //   2.0000000000000000000000000000000000000000000000000 )
+    //   = -0.24858442708494893408462856109734087389683955309853
+
+    // and a comparison with Wolfram shows agreement to the expected precision.
+    // -0.24858442708494893408462856109734087389683955309853  Boost.Math
+    // -0.24858442708494893408462856109734087389683955309853  Wolfram
+
+    // Taking care not to fall into the awaiting pit, we ensure that ALL arguments passed are of the
+    // appropriate 50-digit precision and do NOT suffer from precision reduction to that of type double,
+    // We do NOT write:
+    std::cout << "jacobi_zeta<cpp_bin_float_50>(0.9, 2.)  = " << jacobi_zeta<cpp_bin_float_50>(0.9, 2) << std::endl;
+    // jacobi_zeta(0.90000000000000000000000000000000000000000000000000,
+    //   2.0000000000000000000000000000000000000000000000000 )
+    //   = -0.24858442708494895921459900494815797085727097762164  << Wrong at about 17th digit!
+    //     -0.24858442708494893408462856109734087389683955309853  Wolfram
+  }
+  catch (std::exception const& ex)
+  {
+    // Lacking try&catch blocks, the program will abort after any throw, whereas the
+    // message below from the thrown exception will give some helpful clues as to the cause of the problem.
+    std::cout << "\n""Message from thrown exception was:\n   " << ex.what() << std::endl;
+    // An example of message:
+    // std::cout << " = " << jacobi_zeta(2, 0.5) << std::endl;
+    // Message from thrown exception was:
+    // Error in function boost::math::ellint_k<long double>(long double) : Got k = 2, function requires |k| <= 1
+    // Shows that first parameter is k and is out of range, as the definition in docs jacobi_zeta(T1 k, T2 phi);
+  }
+} // int main()