The window "Curve: X(t)" in this demonstration displays the curve X(t) = (cos(t), sin(t), cos(2t)/c), the point X(t0), and the tangent, normal, and binormal vectors T(t0), P(t0), and B(t0), with their tails at that point.

The window "Spherical Images: T, P, B" displays the same three vectors with their tails at the origin, the sphere on which their heads are constrained to lie, and the tangential indicatrix.

The total length of the tangential indicatrix, displayed in a readout in the control window, is called the total curvatuve of the curve X(t). From Fenchel's theorem, this quantity is always greater than or equal to 4π. It is possible to change c, t0, and X(t) in the control window. It is also possible to set X(t) equal to circle(t) or spacecardioid(t), listed in the control window.