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165 lines
4.4 KiB
C++
165 lines
4.4 KiB
C++
// Copyright Paul A. Bristow 2013.
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// Copyright Nakhar Agrawal 2013.
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// Copyright John Maddock 2013.
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// Copyright Christopher Kormanyos 2013.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#pragma warning (disable : 4100) // unreferenced formal parameter.
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#pragma warning (disable : 4127) // conditional expression is constant.
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//#define BOOST_MATH_OVERFLOW_ERROR_POLICY ignore_error
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#include <boost/multiprecision/cpp_dec_float.hpp>
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#include <boost/math/special_functions/bernoulli.hpp>
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#include <iostream>
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/* First 50 from 2 to 100 inclusive: */
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/* TABLE[N[BernoulliB[n], 200], {n,2,100,2}] */
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//SC_(0.1666666666666666666666666666666666666666),
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//SC_(-0.0333333333333333333333333333333333333333),
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//SC_(0.0238095238095238095238095238095238095238),
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//SC_(-0.0333333333333333333333333333333333333333),
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//SC_(0.0757575757575757575757575757575757575757),
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//SC_(-0.2531135531135531135531135531135531135531),
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//SC_(1.1666666666666666666666666666666666666666),
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//SC_(-7.0921568627450980392156862745098039215686),
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//SC_(54.9711779448621553884711779448621553884711),
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int main()
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{
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try
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{ // It is always wise to use try'n'catch blocks around Boost.Math function
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// so that informative error messages will be displayed.
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//[bernoulli_example_1
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/*`A simple example computes the value of `Bernoulli(2)` where the return type
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is `double`.
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[hint All odd Bernoulli numbers (> 1) are zero, so the parameter value 2 computes B[sub 4]. ]
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*/
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std::cout
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<< std::setprecision(std::numeric_limits<double>::digits10)
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<< boost::math::bernoulli_b2n<double>(2) << std::endl;
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/*` So B[sub 4] == -1/30 == -0.0333333333333333
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If we use Boost.Multiprecision and its 50 decimal digit floating-point type `cpp_dec_float_50`,
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we can calculate the value of much larger numbers like `Bernoulli(100)`
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and also obtain much higher precision.
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*/
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std::cout
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<< std::setprecision(std::numeric_limits<boost::multiprecision::cpp_dec_float_50>::digits10)
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<< boost::math::bernoulli_b2n<boost::multiprecision::cpp_dec_float_50>(100) << std::endl;
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//] //[/bernoulli_example_1]
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//[bernoulli_example_2
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/*`We can compute and save all the float-precision Bernoulli numbers from one call.
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*/
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std::vector<float> bn; // Space for all the 32-bit `float` precision Bernoulli numbers.
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// Start with Bernoulli number 0.
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boost::math::bernoulli_b2n<float>(0, 32, std::back_inserter(bn)); // Fill vector with even Bernoulli numbers.
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for(size_t i = 0; i < bn.size(); i++)
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{ // Show vector of even Bernoulli numbers, showing all significant decimal digits.
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std::cout << std::setprecision(std::numeric_limits<float>::digits10)
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<< i*2 << ' '
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<< bn[i]
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<< std::endl;
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}
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//] //[/bernoulli_example_2]
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}
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catch(const std::exception&)
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{
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}
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//[bernoulli_example_3
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/*`Of course, for any floating-point type, there is a maximum Bernoulli number than can be computed
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before it overflows the exponent.
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If we try to compute too high a Bernoulli number, an exception will be thrown,
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*/
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try{
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std::cout
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<< std::setprecision(std::numeric_limits<float>::digits10)
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<< "Bernoulli number " << 33 * 2 <<std::endl;
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std::cout << boost::math::bernoulli_b2n<float>(33) << std::endl;
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}
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catch (std::exception ex)
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{
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std::cout << "Thrown Exception caught: " << ex.what() << std::endl;
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}
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/*`
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and (provided 'try'n'catch' blocks are used) we will get a helpful error message.
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*/
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//] //[/bernoulli_example_3]
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} // int main()
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/*
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//[bernoulli_output_1
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-3.6470772645191354362138308865549944904868234686191e+215
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//] //[/bernoulli_output_1]
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//[bernoulli_output_2
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0 1
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2 0.166667
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4 -0.0333333
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6 0.0238095
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8 -0.0333333
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10 0.0757576
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12 -0.253114
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14 1.16667
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16 -7.09216
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18 54.9712
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20 -529.124
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22 6192.12
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24 -86580.3
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26 1.42552e+006
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28 -2.72982e+007
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30 6.01581e+008
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32 -1.51163e+010
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34 4.29615e+011
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36 -1.37117e+013
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38 4.88332e+014
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40 -1.92966e+016
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42 8.41693e+017
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44 -4.03381e+019
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46 2.11507e+021
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48 -1.20866e+023
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50 7.50087e+024
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52 -5.03878e+026
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54 3.65288e+028
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56 -2.84988e+030
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58 2.38654e+032
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60 -2.14e+034
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62 2.0501e+036
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//] //[/bernoulli_output_2]
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//[bernoulli_output_3
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Bernoulli number 66
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Thrown Exception caught: Error in function boost::math::bernoulli_b2n<float>(n): Overflow evaluating function at 33
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//] //[/bernoulli_output_3]
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*/
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