public Vector3d TangentVector2d(Point point)
{
if (!this.ContainsOnCircumference(point))
{
return(null);
}
double norm = this.vector3d_0.Norm;
double norm2 = this.vector3d_1.Norm;
Vector3d vector3d = new Vector3d(point - this.point_0);
Vector3d vector3d2 = vector3d.ProjectParallelOn(this.vector3d_0);
Vector3d vector3d3 = vector3d.ProjectParallelOn(this.vector3d_1);
double num = (double)Math.Sign(Vector3d.Dot(vector3d2, this.vector3d_0)) * vector3d2.Norm;
double num2 = (double)Math.Sign(Vector3d.Dot(vector3d3, this.vector3d_1)) * vector3d3.Norm;
double scalar = -norm / norm2 * num2;
double scalar2 = norm2 / norm * num;
return(scalar * this.vector3d_0.Normalize() + scalar2 * this.vector3d_1.Normalize());
}
