mirror of
https://github.com/boostorg/math.git
synced 2026-07-23 13:44:09 +00:00
Matt Borland
75 lines
2.2 KiB
C++
75 lines
2.2 KiB
C++
/*
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* Copyright Nick Thompson, 2019
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* Copyright Matt Borland, 2026
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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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* Module build check for boost::math::tools::agm. It exercises the exported
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* arithmetic-geometric mean entry point when the test is built against the
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* boost.math module. The double and float expected values mirror the
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* assertions in agm_test.cpp.
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*/
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#ifndef BOOST_MATH_BUILD_MODULE
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#include <boost/math/tools/agm.hpp>
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#else
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import boost.math;
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#endif
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#ifndef BOOST_MATH_BUILD_MODULE
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#include <cmath>
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#endif
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#include "math_unit_test.hpp"
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using boost::math::tools::agm;
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using std::sqrt;
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// Gauss's constant G = 1/agm(sqrt(2), 1). http://oeis.org/A014549/constant
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template <typename Real>
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void test_gauss_constant()
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{
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const double G_expected = 0.83462684167407318628142973279904680899399301349034700244982737010368199270952641186969116035127532412906785;
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Real G_computed = 1 / agm(Real(sqrt(Real(2))), Real(1));
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CHECK_ULP_CLOSE(G_expected, G_computed, 2);
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}
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// All of these are mathematically-exact properties of the agm.
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template <typename Real>
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void test_scaling()
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{
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Real a = 2;
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Real g = 1;
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Real scale = 7;
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// Homogeneity: agm(k*x, k*y) = k*agm(x, y).
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Real expected = agm(scale * a, scale * g);
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Real computed = scale * agm(a, g);
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CHECK_ULP_CLOSE(expected, computed, 2);
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// agm(a, 0) = 0 and agm(0, 0) = 0.
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CHECK_ULP_CLOSE(Real(0), agm(a, Real(0)), 0);
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CHECK_ULP_CLOSE(Real(0), agm(Real(0), Real(0)), 0);
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// agm(x, x) = x.
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CHECK_ULP_CLOSE(Real(1), agm(Real(1), Real(1)), 0);
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CHECK_ULP_CLOSE(Real(7), agm(Real(7), Real(7)), 0);
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// Composition identity: agm(x, y) = agm((x+y)/2, sqrt(x*y)).
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// With x = 3, y = 1: (x+y)/2 = 2, sqrt(x*y) = sqrt(3).
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expected = agm(Real(3), Real(1));
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computed = agm(Real(2), Real(sqrt(Real(3))));
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CHECK_ULP_CLOSE(expected, computed, 0);
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}
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int main()
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{
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test_gauss_constant<double>();
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test_scaling<double>();
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test_gauss_constant<float>();
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test_scaling<float>();
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return boost::math::test::report_errors();
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}
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