KOKO\Mimi
54 lines
1.5 KiB
C++
54 lines
1.5 KiB
C++
#include <fesa/fem/gauss_rule.hpp>
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#include <array>
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#include <limits>
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#include <stdexcept>
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#include <gtest/gtest.h>
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namespace {
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TEST(Quadrature, OnePointRuleIntegratesDegreeZeroAndOneExactly) {
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const auto rule = fesa::gauss_rule_1d(1);
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ASSERT_EQ(rule.size(), 1);
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EXPECT_DOUBLE_EQ(rule[0].weight, 2.0);
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EXPECT_DOUBLE_EQ(rule[0].weight * rule[0].xi, 0.0);
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}
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TEST(Quadrature, TwoPointRuleIntegratesThroughDegreeThreeWithinRoundoff) {
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const auto rule = fesa::gauss_rule_1d(2);
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ASSERT_EQ(rule.size(), 2);
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double degree_zero = 0.0;
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double degree_one = 0.0;
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double degree_two = 0.0;
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double degree_three = 0.0;
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for (const auto& point : rule) {
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const double xi_squared = point.xi * point.xi;
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degree_zero += point.weight;
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degree_one += point.weight * point.xi;
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degree_two += point.weight * xi_squared;
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degree_three += point.weight * xi_squared * point.xi;
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}
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// Sixteen ulps at unit scale cover only the rounding in these short sums.
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constexpr double tolerance =
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16.0 * std::numeric_limits<double>::epsilon();
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EXPECT_NEAR(degree_zero, 2.0, tolerance);
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EXPECT_NEAR(degree_one, 0.0, tolerance);
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EXPECT_NEAR(degree_two, 2.0 / 3.0, tolerance);
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EXPECT_NEAR(degree_three, 0.0, tolerance);
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}
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TEST(Quadrature, RejectsUnsupportedOrders) {
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for (const int order : std::array{0, 3, -1}) {
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EXPECT_THROW(
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static_cast<void>(fesa::gauss_rule_1d(order)),
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std::invalid_argument);
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}
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}
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} // namespace
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