math/test/jacobi_test.cpp

117 lines
3.6 KiB
C++

/*
* Copyright Nick Thompson, 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)
*/
#include "math_unit_test.hpp"
#include <numeric>
#include <utility>
#include <random>
#include <cmath>
#include <boost/math/special_functions/jacobi.hpp>
#ifdef BOOST_HAS_FLOAT128
#include <boost/multiprecision/float128.hpp>
using boost::multiprecision::float128;
#endif
using std::abs;
using boost::math::jacobi;
using boost::math::jacobi_derivative;
template<typename Real>
void test_to_quadratic()
{
Real h = 1/Real(8);
for (Real alpha = -1 + h; alpha < 2; alpha += h) {
for (Real beta = -1 + h; beta < 2; beta += h) {
for (Real x = -1; x < 1; x += h) {
Real expected = 1;
Real computed = jacobi(0, alpha, beta, x);
CHECK_ULP_CLOSE(expected, computed, 0);
expected = (alpha + 1) + (alpha + beta +2)*(x-1)/2;
computed = jacobi(1, alpha, beta, x);
CHECK_ULP_CLOSE(expected, computed, 0);
expected = (alpha + 1)*(alpha+2)/2 + (alpha + 2)*(alpha + beta + 3)*(x-1)/2 + (alpha + beta + 3)*(alpha + beta + 4)*(x-1)*(x-1)/8;
computed = jacobi(2, alpha, beta, x);
CHECK_ULP_CLOSE(expected, computed, 1);
}
}
}
}
template<typename Real>
void test_symmetry()
{
Real h = 1/Real(4);
for (Real alpha = -1 + h; alpha < 2; alpha += h) {
for (Real beta = -1 + h; beta < 2; beta += h) {
for (Real x = -1; x < 1; x += h) {
for (size_t n = 0; n < 20; n += 2)
{
Real expected = jacobi(n, beta, alpha , -x);
Real computed = jacobi(n, alpha, beta, x);
CHECK_ULP_CLOSE(expected, computed, 0);
expected = jacobi(n+1, beta, alpha, -x);
computed = -jacobi(n+1, alpha, beta, x);
CHECK_ULP_CLOSE(expected, computed, 0);
}
}
}
}
}
template<typename Real>
void test_derivative()
{
Real h = 1/Real(4);
for (Real alpha = -1 + h; alpha < 2; alpha += h) {
for (Real beta = -1 + h; beta < 2; beta += h) {
for (Real x = -1; x < 1; x += h) {
Real expected = 0;
Real computed = jacobi_derivative(0, alpha, beta, x, 1);
CHECK_ULP_CLOSE(expected, computed, 0);
expected = (alpha + beta + 2)/2;
computed = jacobi_derivative(1, alpha, beta, x, 1);
CHECK_ULP_CLOSE(expected, computed, 0);
expected = (alpha + 2)*(alpha + beta + 3)/2 + (alpha + beta + 3)*(alpha + beta + 4)*(x-1)/4;
computed = jacobi_derivative(2, alpha, beta, x, 1);
CHECK_ULP_CLOSE(expected, computed, 0);
expected = (alpha + beta + 3)*(alpha + beta + 4)/4;
computed = jacobi_derivative(2, alpha, beta, x, 2);
CHECK_ULP_CLOSE(expected, computed, 0);
}
}
}
}
int main()
{
test_to_quadratic<double>();
test_to_quadratic<long double>();
test_symmetry<float>();
test_symmetry<double>();
test_symmetry<long double>();
test_derivative<float>();
test_derivative<double>();
test_derivative<long double>();
#ifdef BOOST_HAS_FLOAT128
test_to_quadratic<boost::multiprecision::float128>();
test_symmetry<boost::multiprecision::float128>();
test_derivative<boost::multiprecision::float128>();
#endif
return boost::math::test::report_errors();
}