[en] We present a detailed description of N=2 stationary BPS multicenter black hole solutions for quadratic prepotentials with an arbitrary number of centers and scalar fields making a systematic use of the algebraic properties of the matrix of second derivatives of the prepotential, S, which in this case is a scalar-independent matrix. In particular we obtain bounds on the physical parameters of the multicenter solution such as horizon areas and ADM mass. We discuss the possibility and convenience of setting up a basis of the symplectic vector space built from charge eigenvectors of the S, the set of vectors (P_±q_a) with P_±S-eigenspace projectors. The anti-involution matrix S can be understood as a Freudenthal duality x-tilde=Sx. We show that this duality can be generalized to “Freudenthal transformations” x→λexp (θS)x=ax+bx-tilde under which the horizon area, ADM mass and intercenter distances scale up leaving constant the scalars at the fixed points. In the special case λ=1, “S-rotations”, the transformations leave invariant the solution. The standard Freudenthal duality can be written as x-tilde=exp((π/2)S)x. We argue that these generalized transformations leave invariant not only the quadratic prepotential theories but also the general stringy extremal quartic form Δ_4, Δ_4(x)=Δ_4(cos θx+sin θx-tilde) and therefore its entropy at lowest order