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#include "Base/Math/Bessel.h"
#include "Tests/GTestWrapper/google_test.h"
// Test complex Bessel function J1
TEST(Bessel, BesselJ1)
{
#ifdef BA_OTHER_ARCH
const double eps = 4.7e-13; // i386 about as bad as this
#else
const double eps = 4.7e-16; // more than twice the machine precision
#endif
complex_t res;
// Test four arbitrary function values.
// Reference values are computed using dev-tools/math/cbesselJ01.c,
// from which BesselJ1 has been derived. So this is _not_ an independent
// for numeric accuracy, but only for invariance.
// However, the four specific results below have also been checked against the
// online calculator http://keisan.casio.com/exec/system/1180573474.
// Agreement is excellent, except for the dominantly imaginary argument .01+100i.
// In conclusion, Bessel::J1 is clearly good enough for our purpose.
res = Math::Bessel::J1(complex_t(0.8, 1.5));
EXPECT_NEAR(res.real(), 0.72837687825769404, eps * std::abs(res)); // Keisan ..69398...
EXPECT_NEAR(res.imag(), 0.75030568686427268, eps * std::abs(res)); // Keisan ..27264...
res = Math::Bessel::J1(complex_t(1e-2, 1e2));
EXPECT_NEAR(res.real(), 1.0630504683139779e40, eps * std::abs(res)); // Keisan 1.063015...
EXPECT_NEAR(res.imag(), 1.0683164984973165e42, eps * std::abs(res)); // Keisan ..73162...
res = Math::Bessel::J1(complex_t(-1e2, 1e-2));
EXPECT_NEAR(res.real(), 0.077149198549289394, eps * std::abs(res)); // Keisan ..89252...
EXPECT_NEAR(res.imag(), 2.075766253119904e-4, eps * std::abs(res)); // Keisan ..19951...
res = Math::Bessel::J1(complex_t(7, 9));
EXPECT_NEAR(res.real(), 370.00180888861155, eps * std::abs(res)); // Keisan ..61107...
EXPECT_NEAR(res.imag(), 856.00300811057934, eps * std::abs(res)); // Keisan ..57940...
}
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