For 2D functions, Visual Calculus has the ability of doing curvature related calculating and graphing. Following figure shows two curvature circles at x=-3 and x=2.5 on the graph of function y=cos(x).

The curvature and the center of curvature can also be calculated. In this example, you can get the following results in Result Editor:

 Curvature circle:
     Position: x=-3, y=-.9899925
         Curvature: .9611386
         Radius of curvature: 1.040433
         Center of curvature: x=-3.145385, y=4.023233E-02
     Position: x=2.5, y=-.8011436
         Curvature: .5061505
         Radius of curvature: 1.975697
         Center of curvature: x=3.514582, y=.8941441

Math Software -> Graph Calculus -> Curvature Circle, Radius of Curvature, Center of Curvature