30 lines
1.1 KiB
C++
30 lines
1.1 KiB
C++
/*
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* Copyright Nick Thompson, 2017
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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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*
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* This example shows to to numerically integrate a periodic function using the adaptive_trapezoidal routine provided by boost.
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*/
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#include <iostream>
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#include <cmath>
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#include <limits>
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#include <boost/math/quadrature/trapezoidal.hpp>
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int main()
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{
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using boost::math::constants::two_pi;
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using boost::math::constants::third;
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using boost::math::quadrature::trapezoidal;
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// This function has an analytic form for its integral over a period: 2pi/3.
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auto f = [](double x) { return 1/(5 - 4*cos(x)); };
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double Q = trapezoidal(f, (double) 0, two_pi<double>());
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std::cout << std::setprecision(std::numeric_limits<double>::digits10);
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std::cout << "The adaptive trapezoidal rule gives the integral of our function as " << Q << "\n";
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std::cout << "The exact result is " << two_pi<double>()*third<double>() << "\n";
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}
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