/// <summary>
/// first derivative at t
/// </summary>
/// <param name="t">the parameter where the derivative is calculated</param>
/// <returns></returns>
public Point Derivative(double t)
{
return(curve.Derivative(t));
}
/// <summary>
/// first derivative at t
/// </summary>
/// <param name="t">the parameter where the derivative is calculated</param>
/// <returns></returns>
public Point Derivative(double t)
{
return(curve.Derivative(t));
}