diff --git a/test/general/test_numerics.cpp b/test/general/test_numerics.cpp new file mode 100644 index 0000000000..c23713d1f3 --- /dev/null +++ b/test/general/test_numerics.cpp @@ -0,0 +1,93 @@ +#include "gtest/gtest.h" +#include "cantera/numerics/polyfit.h" + +using namespace Cantera; + +double polyval(vector_fp& coeffs, double x) { + double sum = 0; + double xn = 1; + for (size_t i = 0; i < coeffs.size(); i++) { + sum += coeffs[i] * xn; + xn *= x; + } + return sum; +} + +TEST(Polyfit, exact_fit) +{ + vector_fp x{0, 0.3, 1.0, 1.5, 2.0, 2.5}; + vector_fp p(6); + vector_fp w(6, 1.0); + for (int i = 0; i < 20; i++) { + vector_fp y{-1.1*i, cos(i), pow(-1,i), 3.2/(i+1), 0.1*i*i, sin(i)}; + int ndeg; + polyfit(6, x.data(), y.data(), w.data(), 5, ndeg, 0, p.data()); + for (size_t j = 0; j < 6; j++) { + EXPECT_NEAR(polyval(p, x[j]), y[j], 1e-12); + } + } +} + +TEST(Polyfit, sequential) +{ + vector_fp x{-1.0, 0.0, 0.5, 1.0, 1.5, 2.0, 3.0}; + vector_fp y{0.6, 1.0, 0.8, 0.4, -0.1, -0.5, -1}; + + // Coefficients calculated using Numpy's polyfit function for polynomials + // of degrees 0 - 5. + std::vector PP{ + {0.17142857142857154}, + {0.66190476190476177, -0.49047619047619029}, + {0.73605442176870761, -0.19387755102040838, -0.14829931972789107}, + {1.0095838335334129, -0.22426970788315401, -0.51300520208083311, + 0.12156862745098072}, + {1.0121336003688943, -0.23102395749454527, -0.51552488317194212, + 0.12746543334778632, -0.0014742014742014889}, + {0.99812799812799835, -0.093488943488944404, -0.61193011193011071, + 0.011452361452361514, 0.10963690963690906, -0.022222222222222105} + }; + + vector_fp w(7, 1.0); + int ndeg; + for (size_t i = 0; i < PP.size(); i++) { + size_t N = i + 1; + vector_fp p(N); + polyfit(7, x.data(), y.data(), w.data(), i, ndeg, 0, p.data()); + ASSERT_EQ(ndeg, (int) i); + for (size_t j = 0; j < N; j++) { + EXPECT_NEAR(PP[i][j], p[j], 1e-14); + } + } +} + +TEST(Polyfit, weighted) +{ + vector_fp x{-1.0, 0.0, 0.5, 1.0, 1.5, 2.0, 3.0}; + vector_fp y{0.6, 1.0, 0.8, 0.4, -0.1, -0.5, -1}; + vector_fp w{25, 1, 1, 1, 1, 1, 100}; // these are the squares of Numpy's weights + + // Coefficients calculated using Numpy's polyfit function for polynomials + // of degrees 0 - 5. + std::vector PP{ + {-0.64153846153846139}, + {0.24582603619381152, -0.41199065966141246}, + {0.64897277949822718, -0.10796777523450461, -0.14749113594542437}, + {1.0095165556633916, -0.22435606362053356, -0.51254844673169053, + 0.12135217568551074}, + {1.0121717322829622, -0.23147507683766383, -0.51492677362711337, + 0.12728869689006062, -0.0014837700620763492}, + {0.998127784554808, -0.093474983983779111, -0.61196784469972776, + 0.011482911646053995, 0.10962944760868476, -0.022222284629403764} + }; + + int ndeg; + for (size_t i = 0; i < PP.size(); i++) { + size_t N = i + 1; + vector_fp p(N); + polyfit(7, x.data(), y.data(), w.data(), i, ndeg, 0, p.data()); + ASSERT_EQ(ndeg, (int) i); + for (size_t j = 0; j < N; j++) { + EXPECT_NEAR(PP[i][j], p[j], 1e-14); + } + } +}