#ifdef _OPENACC
void initialisation_openacc()
{
    char* local_rank_env;
    int local_rank;

    /* Initialisation of OpenACC */
    #pragma acc init

    /* Recovery of the local rank of the process via the environment variable
       set by Slurm, as MPI_Comm_rank cannot be used here because this routine
       is used BEFORE the initialisation of MPI*/

    local_rank_env = getenv("SLURM_LOCALID");

    if (local_rank_env) {
        local_rank = atoi(local_rank_env);
        /* Define the GPU to use via OpenACC */
        acc_set_device_num(local_rank, acc_get_device_type());
    } else {
        printf("Error : impossible to determine the local rank of the process\n");
        exit(1);
    }
}
#endif