return MPI_ERR_ARG;
} else{
simgrid::smpi::Topo_Cart* topo = new simgrid::smpi::Topo_Cart(comm_old, ndims, dims, periodic, reorder, comm_cart);
return MPI_ERR_ARG;
} else{
simgrid::smpi::Topo_Cart* topo = new simgrid::smpi::Topo_Cart(comm_old, ndims, dims, periodic, reorder, comm_cart);