The window "Domain" displays a point C and the
curve C + t(cos(a), sin(a)), where t runs from –1 to 1.
The window "Surface" window displays the surface X(u, v), the image of the curve
from the "Domain" window on this surface, the point X(C + t0(cos(a),
sin(a)), and the frenet frame, osculating, normal, and rectifying
planes, and normal vector to the surface, at that point.
The vectors P,
B, and N are also shown in the "P-B plane" window. The normal curvature
of the curve X(C + t(cos(a), sin(a))) at t0 is given
curvature of X(C + t(cos(a), sin(a))) at t0 times the
of P and N at t0.
It is possible to change C in the "Domain"
clicking and dragging it, and it is possible to change a, t0,
v) in the control window.