The end of one bone within the joint is typically convex, or pointed outward, vs. concave, or rounded inward ... and toes is essential for all daily functions, from activities of daily living ...

Optimization without calculus; geometric programming; convex sets and convex functions; review of linear algebra; linear programming and the simplex method; convex programming; iterative ...

In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.