What is mode Xpansion ? When should it be used ?

[flomnes]

Notable differences src/solver/optimisation/opt_nombre_min_groupes_demarres_couts_demarrage.cpp, some changes in function OPT_AjusterLeNombreMinDeGroupesDemarresCoutsDeDemarrage.

In file src/solver/optimisation/opt_optimisation_lineaire.cpp, only one resolution is done if this mode is enabled (not 2)

if (ProblemeHebdo->Expansion == NON_ANTARES)
    goto OptimisationHebdo;

Day-ahead reserves (solver/optimisation/opt_gestion_second_membre_cas_lineaire.cpp:162, solver/optimisation/opt_gestion_des_bornes_cas_lineaire.cpp:363), but it's dead code since exp && opt2 should always evaluate to false (see above).