public void BesselAtZero()
{
// Normal Bessel \nu = 0
Assert.IsTrue(AdvancedMath.BesselJ(0, 0.0) == 1.0);
Assert.IsTrue(AdvancedMath.BesselJ(0.0, 0.0) == 1.0);
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(0, 0.0)));
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(0.0, 0.0)));
SolutionPair jy0 = AdvancedMath.Bessel(0.0, 0.0);
Assert.IsTrue(jy0.FirstSolutionValue == 1.0);
Assert.IsTrue(jy0.FirstSolutionDerivative == 0.0);
Assert.IsTrue(Double.IsNegativeInfinity(jy0.SecondSolutionValue));
Assert.IsTrue(Double.IsPositiveInfinity(jy0.SecondSolutionDerivative));
// Normal Bessel 0 < \nu < 1
Assert.IsTrue(AdvancedMath.BesselJ(0.1, 0.0) == 0.0);
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(0.1, 0.0)));
SolutionPair jyf = AdvancedMath.Bessel(0.9, 0.0);
Assert.IsTrue(jyf.FirstSolutionValue == 0.0);
Assert.IsTrue(jyf.FirstSolutionDerivative == Double.PositiveInfinity);
Assert.IsTrue(Double.IsNegativeInfinity(jyf.SecondSolutionValue));
Assert.IsTrue(Double.IsPositiveInfinity(jyf.SecondSolutionDerivative));
// Normal Bessel \nu = 1
Assert.IsTrue(AdvancedMath.BesselJ(1, 0.0) == 0.0);
Assert.IsTrue(AdvancedMath.BesselJ(1.0, 0.0) == 0.0);
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(1, 0.0)));
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(1.0, 0.0)));
SolutionPair jy1 = AdvancedMath.Bessel(1.0, 0.0);
Assert.IsTrue(jy1.FirstSolutionValue == 0.0);
Assert.IsTrue(jy1.FirstSolutionDerivative == 0.5);
Assert.IsTrue(Double.IsNegativeInfinity(jy1.SecondSolutionValue));
Assert.IsTrue(Double.IsPositiveInfinity(jy1.SecondSolutionDerivative));
// Normal Bessel \nu > 1
Assert.IsTrue(AdvancedMath.BesselJ(2, 0.0) == 0.0);
Assert.IsTrue(AdvancedMath.BesselJ(1.2, 0.0) == 0.0);
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(2, 0.0)));
Assert.IsTrue(Double.IsNegativeInfinity(AdvancedMath.BesselY(1.2, 0.0)));
SolutionPair jy2 = AdvancedMath.Bessel(1.7, 0.0);
Assert.IsTrue(jy2.FirstSolutionValue == 0.0);
Assert.IsTrue(jy2.FirstSolutionDerivative == 0.0);
Assert.IsTrue(Double.IsNegativeInfinity(jy2.SecondSolutionValue));
Assert.IsTrue(Double.IsPositiveInfinity(jy2.SecondSolutionDerivative));
}
