mp_environ_l Subroutine

   RECURSIVE SUBROUTINE mp_environ_l(numtask, taskid, groupid)
      !! returns number of tasks and task id for a given mpi group
      !! simple and cartesian version.. recursive needed in case of failing mpi_comm_rank.
      !! @note
      !! ..mp_world_setup is gone, use mp_environ instead (i.e. give a groupid explicitly)

      INTEGER, OPTIONAL, INTENT(OUT)                     :: numtask, taskid
      INTEGER, INTENT(IN)                                :: groupid
         !! mpi communicator

      INTEGER                                            :: ierr

      ierr = 0

      IF (PRESENT(numtask)) numtask = 1
      IF (PRESENT(taskid)) taskid = 0
#if defined(__parallel)
      IF (PRESENT(taskid)) THEN
         CALL mpi_comm_rank(groupid, taskid, ierr)
         IF (ierr /= 0) CALL mp_stop(ierr, "mpi_comm_rank @ mp_environ_l")
      END IF

      IF (PRESENT(numtask)) THEN
         CALL mpi_comm_size(groupid, numtask, ierr)
         IF (ierr /= 0) CALL mp_stop(ierr, "mpi_comm_size @ mp_environ_l")
      END IF
#else
      MARK_USED(groupid)
#endif

   END SUBROUTINE mp_environ_l