For a convex set C⊂RdC \subset R^dC⊂Rd, a function f:C→Rf: C \rightarrow Rf:C→R is convex iff(λx+(1−λ)y)≤λf(x)+(1−λ)f(y),∀x,y∈Cand∀λ∈[0,1]f(\lambda x+ (1 - \lambda)y) \le \lambda f(x) + (1 - \lambda)f(y), \forall x, y \in C and \forall \lambda \in [0, 1]f(λx+(1−λ)y)≤λf(x)+(1−λ)f(y),∀x,y∈Cand∀λ∈[0,1]
