concave up

In mathematics, a real-valued function f defined on an interval (or on any convex set C of some vector space) is called concave, if for any two points x and y in its domain C and any t in [0,1], we haveAlso, f(x) is concave on [a, b] if and only if the function −f(x) is convex on [a, b].A function that is concave is often synonymously called concave downward, and a function that is convex is often synonymously called concave upward.
See more at Wikipedia.org...

In mathematics, a real-valued function f defined on an interval (or on any convex subset of some vector space) is called convex, or concave up, if for any two points x and y in its domain C and any t in [0,1], we haveIn other words, a function is convex if and only if its epigraph (the set of points lying on or above the graph) is a convex set. A function is called strictly convex if for any t in (0,1) and
See more at Wikipedia.org...