[Numerics] Simplify gfc3d_nsgs
[Numerics] Simplify gfc3d_nsgs

bremond/siconos,siconos/siconos,radarsat1/siconos,fperignon/siconos,bremond/siconos,bremond/siconos,bremond/siconos,radarsat1/siconos,radarsat1/siconos,siconos/siconos,radarsat1/siconos,siconos/siconos,fperignon/siconos,fperignon/siconos,fperignon/siconos,radarsat1/siconos,siconos/siconos,bremond/siconos,fperignon/siconos