Changes between Version 1 and Version 2 of PDAF3_init_parallel

Timestamp:

Mar 28, 2026, 12:17:41 PM (3 days ago)

Author:

lnerger

Comment:

--

PDAF3_init_parallel

@@ -12 +12 @@
 The interface is the following:
 {{{
-  SUBROUTINE PDAF3_init_parallel(screen, type_parallel, online_coupling, n_modeltasks, dim_ens, &
+  SUBROUTINE PDAF3_init_parallel(screen, type_parallel, online_coupling, dim_ens, n_modeltasks, &
        COMM_model, mype_model, npes_model, COMM_assim, mype_assim, npes_assim, &
        task_id)
 
+    ! Input variables
     INTEGER, INTENT(in)    :: screen          ! >0 for display information about the parallelization setup
-
-    ! Input variables
     INTEGER, INTENT(in) :: type_parallel      ! Type of parallelization (currently not uesed)
     INTEGER, INTENT(in) :: online_cpl         ! 1: online DA coupling, 0: offline DA coupling
     INTEGER, INTENT(in) :: dim_ens            ! Ensemble size
 
-    ! Input variable that might be updated in the routine
+    ! Input variables that might be updated in the routine
     INTEGER, INTENT(inout) :: n_modeltasks    ! Number of model tasks
-    INTEGER, INTENT(out) :: COMM_model        ! Input: Model MPI communicator
+    INTEGER, INTENT(inout) :: COMM_model      ! Input: Model MPI communicator
                                               ! Output: Model communicator split for model tasks
-
     ! Output variables
     INTEGER, INTENT(out) :: npes_model        ! Number of Processs in COMM_model
@@ -42 +40 @@
 * The template and tutorial codes show the use of `PDAF3_init_parallel` in the file `init_parallel_pdaf.F90`.
 * For the offline DA coupling, the routine always sets `n_modeltasks=1` independent of the input value.
+* The routine can be called without a prior initialization of the MPI environment (i.e. call to MPI_init). In this case the routine will initialize MPI and then perform the the parallelization setup according to the values of `n_modeltasks` and `dim_ens`.
+* The value of `n_modeltasks` cannot be larger than the number of processes in the execution of the DA program. If this is the case, the routine sets `n_modeltasks=npes_model`
+* The value of `dim_ens` is used for consistency checking (`n_modeltasks` cannot be larger than `dim_ens`; if this is the case, the routine sets `n_modeltasks=dim_ens`). The check is deactivated with `dim_ens=0` is provided to the routine.