Point of convexity
= Point of convexity
{title2=$g(v)\geq g(v_0)+g'(v_0)(v-v_0)$}
For a differentiable real <function> $g$, a point of <convexity> is a point $v_0$ whose tangent line lies below the entire graph. The <function> need not be <convex> at other points. The <Weierstrass excess function> is exactly the difference between the function and this tangent line when applied to a variational integrand as a function of slope.