[numerics] fix bug in extracting 5x5 diagonal block
[numerics] fix bug in extracting 5x5 diagonal block

radarsat1/siconos,siconos/siconos,radarsat1/siconos,radarsat1/siconos,siconos/siconos,radarsat1/siconos,siconos/siconos,radarsat1/siconos,siconos/siconos