public void FirstDerivative()
{
IInterpolation ip = LinearSpline.Interpolate(_t, _y);
Assert.That(ip.Differentiate(-3.0), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(-2.0), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(-1.5), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(-1.0), Is.EqualTo(-3.0));
Assert.That(ip.Differentiate(-0.5), Is.EqualTo(-3.0));
Assert.That(ip.Differentiate(0.0), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(0.5), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(1.0), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(2.0), Is.EqualTo(1.0));
Assert.That(ip.Differentiate(3.0), Is.EqualTo(1.0));
}
public DemoSample GetSample(long timeMs)
{
long oldTime = sample.t;
sample.t = timeMs * 1000000; // from millisecond to nanosecond
double time = ((double)timeMs) / 1000.0; // from milliseconds to seconds
if (time > TIME_MAX) // return zero speed and acceleration after 20 seconds run time
{
sample.s = sample.x = sample.y = sample.z = 0;
}
else
{
sample.s = (float)(spline.Interpolate(time) / 3.6); // 3.6 = from km/h to m/s
float acceleration = (float)spline.Differentiate(time);
sample.x = acceleration / 10;
sample.y = acceleration / 10;
sample.z = acceleration / 5;
}
// distance : integrate speed over time
// distance += currentSpeed * (t1 - t0) // t1 = currentTime // t0 = oldTime
float deltaTime = (float)(sample.t - oldTime) / 1000000000; // from nanoseconds to seconds
sample.d += sample.s * deltaTime;
return(sample);
}
/// <summary>
/// Differentiates the specified point to get the steepest gradient.
/// </summary>
/// <param name="point">The point.</param>
/// <returns>UV.</returns>
public UV Differentiate(UV point)
{
Index index = this._cellularFloor.FindIndex(point);
if (this.Origins.Contains(this._cellularFloor.Cells[index.I, index.J]))
{
UV vector = this.DefaultState.Location - point;
vector.Unitize();
return(vector);
}
try
{
IInterpolation u_Interpolation = this.interpolation_U(point, index);
IInterpolation v_Interpolation = this.interpolation_V(point, index);
return(new UV(-1 * u_Interpolation.Differentiate(point.U),
-1 * v_Interpolation.Differentiate(point.V)));
}
catch (Exception)
{
}
return(null);
}
