“…In addition, we denote (•) ⊥ as the orthogonal complement of a vector space, V x = ∇V = (∂ V /∂x) the row vector of the partial derivatives of V : R n → R, C 1 the set of continuously differentiable functions, e 1 (resp., e 2 ) the first (resp., second) standard basis vector in R n , e n+1 the (n + 1)-th standard basis vector in R n+1 , R ≤0 the set of real numbers that are less than or equal to zero, and sgn(x) the sign function (R\{0} → {±1}) that maps to {1}, if x > 0; {−1}, otherwise. Moreover, in accordance with [23], letξ ∈ R n , we defineξ ⊥ ∈ R (n−1)×n as a matrix with orthonormal rows andξ ⊥ξ = 0. Finally, in agreement with [2,4], denote M 0 (resp., M 0), if a matrix M = M T ∈ R n×n is positive definite (resp., semidefinite).…”