public void LinearInterpolatorTests_CanDifferentiate()
{
var interp = new LinearInterpolatorFlatExtrap(new double[] { 5, 10 }, new double[] { 5, 10 });
Assert.Equal(0, interp.FirstDerivative(0));
Assert.Equal(0, interp.FirstDerivative(20));
Assert.Equal(1.0, interp.FirstDerivative(6));
Assert.Equal(0, interp.SecondDerivative(0));
Assert.Equal(0, interp.SecondDerivative(20));
Assert.Equal(0.5, interp.SecondDerivative(5));
var interp2 = new LinearInterpolator(new double[] { 5, 10 }, new double[] { 5, 10 });
Assert.Equal(1.0, interp2.FirstDerivative(0));
Assert.Equal(1.0, interp2.FirstDerivative(20));
Assert.Equal(1.0, interp2.FirstDerivative(6));
Assert.Equal(0.0, interp2.SecondDerivative(0));
Assert.Equal(0.0, interp2.SecondDerivative(20));
Assert.Equal(1.0, interp2.SecondDerivative(5));
var interp3 = new LinearInterpolatorFlatExtrapNoBinSearch(new double[] { 5, 10 }, new double[] { 5, 10 });
Assert.Equal(0, interp3.FirstDerivative(0));
Assert.Equal(0, interp3.FirstDerivative(20));
Assert.Equal(1.0, interp3.FirstDerivative(6), 6);
Assert.Equal(0, interp3.SecondDerivative(0));
Assert.Equal(0, interp3.SecondDerivative(20));
Assert.Equal(0.0, interp3.SecondDerivative(5), 6);
}
public void LinearInterpolatorTests_CanExtrapolate()
{
IInterpolator1D interp = new LinearInterpolator(new double[] { 5, 10 }, new double[] { 5, 10 });
Assert.Equal(0, interp.Interpolate(0.0));
Assert.Equal(7.5, interp.Interpolate(7.5));
Assert.Equal(100, interp.Interpolate(100));
Assert.Equal(1, interp.FirstDerivative(0));
Assert.Equal(1, interp.FirstDerivative(5));
Assert.Equal(1, interp.FirstDerivative(100));
Assert.Equal(0, interp.SecondDerivative(0));
Assert.Equal(1, interp.SecondDerivative(5));
Assert.Equal(0, interp.SecondDerivative(100));
interp = new LinearInterpolatorFlatExtrap(new double[] { 5, 10 }, new double[] { 5, 10 });
Assert.Equal(5, interp.Interpolate(0.0));
Assert.Equal(7.5, interp.Interpolate(7.5));
Assert.Equal(10, interp.Interpolate(100));
Assert.Equal(0, interp.FirstDerivative(0));
Assert.Equal(1, interp.FirstDerivative(5));
Assert.Equal(0, interp.FirstDerivative(100));
Assert.Equal(0, interp.SecondDerivative(0));
Assert.Equal(0.5, interp.SecondDerivative(5));
Assert.Equal(0, interp.SecondDerivative(100));
}