/// <summary>
/// Computes the unit tangent vector to the curve at point t
/// </summary>
/// <param name="t"></param>
/// <returns></returns>
public Double2 TangentAt(double t)
{
var d = Derivative.At(t);
if (DoubleUtils.RoughlyZero(d))
{
return(Derivative.TangentAt(t));
}
return(d.Normalized);
}