Dear PETSc/Tao team, I think there might be a bug in the Tao ALMM class: In the function TaoALMMComputeAugLagAndGradient_Private(), see, eg. https://petsc.org/release/src/tao/constrained/impls/almm/almm.c.html#TAOALMM line 648 the gradient seems to be wrong. The given function and gradient computation is Lc = F + Ye^TCe + Yi^T(Ci - S) + 0.5*mu*[Ce^TCe + (Ci - S)^T(Ci - S)], dLc/dX = dF/dX + Ye^TAe + Yi^TAi + 0.5*mu*[Ce^TAe + (Ci - S)^TAi], but I think the gradient should be (without 0.5) dLc/dX = dF/dX + Ye^TAe + Yi^TAi + mu*[Ce^TAe + (Ci - S)^TAi]. Kind regards, Stephan Köhler -- Stephan Köhler TU Bergakademie Freiberg Institut für numerische Mathematik und Optimierung Akademiestraße 6 09599 Freiberg Gebäudeteil Mittelbau, Zimmer 2.07 Telefon: +49 (0)3731 39-3173 (Büro)