93 lines
3 KiB
C++
93 lines
3 KiB
C++
#include "gtest/gtest.h"
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#include "cantera/numerics/polyfit.h"
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using namespace Cantera;
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double polyval(vector_fp& coeffs, double x) {
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double sum = 0;
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double xn = 1;
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for (size_t i = 0; i < coeffs.size(); i++) {
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sum += coeffs[i] * xn;
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xn *= x;
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}
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return sum;
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}
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TEST(Polyfit, exact_fit)
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{
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vector_fp x{0, 0.3, 1.0, 1.5, 2.0, 2.5};
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vector_fp p(6);
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vector_fp w(6, 1.0);
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for (int i = 0; i < 20; i++) {
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vector_fp y{-1.1*i, cos(i), pow(-1,i), 3.2/(i+1), 0.1*i*i, sin(i)};
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int ndeg;
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polyfit(6, x.data(), y.data(), w.data(), 5, ndeg, 0, p.data());
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for (size_t j = 0; j < 6; j++) {
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EXPECT_NEAR(polyval(p, x[j]), y[j], 1e-12);
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}
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}
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}
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TEST(Polyfit, sequential)
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{
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vector_fp x{-1.0, 0.0, 0.5, 1.0, 1.5, 2.0, 3.0};
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vector_fp y{0.6, 1.0, 0.8, 0.4, -0.1, -0.5, -1};
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// Coefficients calculated using Numpy's polyfit function for polynomials
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// of degrees 0 - 5.
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std::vector<vector_fp> PP{
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{0.17142857142857154},
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{0.66190476190476177, -0.49047619047619029},
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{0.73605442176870761, -0.19387755102040838, -0.14829931972789107},
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{1.0095838335334129, -0.22426970788315401, -0.51300520208083311,
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0.12156862745098072},
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{1.0121336003688943, -0.23102395749454527, -0.51552488317194212,
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0.12746543334778632, -0.0014742014742014889},
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{0.99812799812799835, -0.093488943488944404, -0.61193011193011071,
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0.011452361452361514, 0.10963690963690906, -0.022222222222222105}
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};
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vector_fp w(7, 1.0);
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int ndeg;
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for (size_t i = 0; i < PP.size(); i++) {
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size_t N = i + 1;
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vector_fp p(N);
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polyfit(7, x.data(), y.data(), w.data(), i, ndeg, 0, p.data());
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ASSERT_EQ(ndeg, (int) i);
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for (size_t j = 0; j < N; j++) {
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EXPECT_NEAR(PP[i][j], p[j], 1e-14);
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}
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}
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}
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TEST(Polyfit, weighted)
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{
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vector_fp x{-1.0, 0.0, 0.5, 1.0, 1.5, 2.0, 3.0};
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vector_fp y{0.6, 1.0, 0.8, 0.4, -0.1, -0.5, -1};
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vector_fp w{25, 1, 1, 1, 1, 1, 100}; // these are the squares of Numpy's weights
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// Coefficients calculated using Numpy's polyfit function for polynomials
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// of degrees 0 - 5.
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std::vector<vector_fp> PP{
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{-0.64153846153846139},
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{0.24582603619381152, -0.41199065966141246},
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{0.64897277949822718, -0.10796777523450461, -0.14749113594542437},
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{1.0095165556633916, -0.22435606362053356, -0.51254844673169053,
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0.12135217568551074},
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{1.0121717322829622, -0.23147507683766383, -0.51492677362711337,
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0.12728869689006062, -0.0014837700620763492},
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{0.998127784554808, -0.093474983983779111, -0.61196784469972776,
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0.011482911646053995, 0.10962944760868476, -0.022222284629403764}
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};
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int ndeg;
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for (size_t i = 0; i < PP.size(); i++) {
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size_t N = i + 1;
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vector_fp p(N);
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polyfit(7, x.data(), y.data(), w.data(), i, ndeg, 0, p.data());
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ASSERT_EQ(ndeg, (int) i);
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for (size_t j = 0; j < N; j++) {
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EXPECT_NEAR(PP[i][j], p[j], 1e-14);
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}
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}
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}
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