KOKO\Mimi
72 lines
2.2 KiB
C++
72 lines
2.2 KiB
C++
#include <fesa/fem/line2_shape.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(ShapeFunction, InterpolatesBothEndpoints) {
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const auto first_endpoint = fesa::line2_shape(-1.0);
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const auto second_endpoint = fesa::line2_shape(1.0);
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EXPECT_DOUBLE_EQ(first_endpoint[0], 1.0);
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EXPECT_DOUBLE_EQ(first_endpoint[1], 0.0);
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EXPECT_DOUBLE_EQ(second_endpoint[0], 0.0);
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EXPECT_DOUBLE_EQ(second_endpoint[1], 1.0);
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}
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TEST(ShapeFunction, FormsPartitionOfUnityWithinRoundoff) {
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for (const double xi : std::array{-1.0, -0.25, 0.0, 0.4, 1.0}) {
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const auto shape = fesa::line2_shape(xi);
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// Four ulps at unit scale cover the two affine evaluations and sum.
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constexpr double tolerance =
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4.0 * std::numeric_limits<double>::epsilon();
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EXPECT_NEAR(shape[0] + shape[1], 1.0, tolerance) << "xi=" << xi;
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}
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}
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TEST(ShapeFunction, DerivativesSumToZeroAtEveryNaturalCoordinate) {
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for (const double xi : std::array{-1.0, -0.25, 0.0, 0.4, 1.0}) {
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const auto derivative = fesa::line2_shape_derivative(xi);
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EXPECT_DOUBLE_EQ(derivative[0], -0.5);
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EXPECT_DOUBLE_EQ(derivative[1], 0.5);
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EXPECT_DOUBLE_EQ(derivative[0] + derivative[1], 0.0);
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}
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}
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TEST(Jacobian, ReturnsHalfThePhysicalLength) {
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EXPECT_DOUBLE_EQ(fesa::line2_jacobian(4.0), 2.0);
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EXPECT_DOUBLE_EQ(fesa::line2_jacobian(0.25), 0.125);
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}
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TEST(Jacobian, DoesNotAdjustSmallPositiveFiniteLengths) {
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constexpr double length = 1.0e-300;
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EXPECT_DOUBLE_EQ(fesa::line2_jacobian(length), length / 2.0);
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}
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TEST(Jacobian, RejectsNonpositiveAndNonfiniteLengths) {
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const double infinity = std::numeric_limits<double>::infinity();
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const double nan = std::numeric_limits<double>::quiet_NaN();
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for (const double length : std::array{0.0, -1.0, infinity, nan}) {
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EXPECT_THROW(
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static_cast<void>(fesa::line2_jacobian(length)),
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std::invalid_argument);
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}
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}
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TEST(Jacobian, RejectsLengthWhoseHalfUnderflowsToZero) {
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EXPECT_THROW(
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static_cast<void>(fesa::line2_jacobian(
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std::numeric_limits<double>::denorm_min())),
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std::invalid_argument);
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}
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} // namespace
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