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ISSUES.md

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Known Issues

Known problems with M-M.E.S.S. itself

  • It is essential to remove all earlier M-M.E.S.S. versions from the search path and uninstall previous versions of the toolbox. Otherwise conflicts are almost guaranteed.
  • The octave dense Riccati solvers can not handle indefinite right-hand-sides. These can occur in the mess_solve_projected_eqn routine.
  • The mess_care has been observed to work less accurate in octave, when octave is compiled with GCC before version 5. That means, on RHEL/CentOS/ScientificLinux 6/7, Ubuntu 14.04, SLES 11/12 one should not rely on the default system GCC for the octave compilation. This may also affect other routines.
  • The dae_2_so and dae_3_so usfs compute the wrong residuals when mess_res2_norms is used. This can be fixed along the lines of the current dae_2 implementation. Internal residual computations do not use mess_res2_norms, but rely on known residual factors.
  • The current dae_1 implementation is overwriting eqn.B and eqn.C with the ones on the hidden manifold.
  • The mess_splitting_dre requires the input eqn.Rinv. This implements E'*d/dt X(t)*E = -C'*C - E'*X(t)*A - A'*X(t)*E + E'*X(t)*B*Rinv*B'*X(t)*E (T). The input is not used for the computation of the feedback matrix K(t) = E'*X(t)*B.
  • mess_bdf_dre and mess_rosenbrock_dre.m do not use the input eqn.Rinv.
  • mess_splitting_dre does not give the expected order of approximation in the LTV case for order larger 2.
  • mess_splitting_dre works for the LTV case only if A(t)*A(s)=A(s)*A(t). This is not checked in the code and has to be ensured by the user.
  • BDF solvers can currently not be used with line-search activated in the inner Newton-Kleinman solves.
  • mess_lrnmin LDL_T mode with line-search is sometimes unstable in Octave.
  • mess_tangential_irka was observed to converge exceptionally slow using MATLAB R2019b on certain Intel Sandy bridge processors.
  • mess_lrradi can crash in rare cases inside mess_RADI_get_shifts_hamOpti_generalized, probably due to an economy size QR with incompatible dimensions.
  • mess_res2_norms was observed to be less accurate using MATLAB R2019b on certain Intel Westmere processors.
  • exp_action in the splitting methods does not work with its 'Krylov' method when dae_2 usfs are used.

Compatibility with other Software

  • The sssMOR toolbox from MORLab @ TUM contains an earlier version of M-M.E.S.S. this may lead to conflicts with our internal data-management. Also some wrong number of inputs or outputs error messages can appear.