= PDAF_assimilate_prepost_si = 

This page documents the routine `PDAF_assimilate_prepost_si` of PDAF. It is basically an alias for the routine `PDAF_prepost_si` and we generally recommend to rather use `[wiki:PDAF_prepost_si]` to avoid the naming confusion that `PDAF_assimilate_prepost_si` holds 'assimilate' in its name, but is not performing assimilation.

The routine is typically called in `assimilate_pdaf` or directly in the model code.

The routine `PDAF_assimilate_prepost_si` is an alternative to the routines `PDAF_assimilate_X_si` where 'X' is the name of a filter method. 
The routine is used in the 'fully-parallel' implementation variant of PDAF. The purpose of `PDAF_assimilate_prepost_si` is to collect the ensemble information on the processes usually doing the filter analysis. However, in the case of `PDAF_assimilate_prepost_si`, no filter analysis step is performed when the ensemble integration is complete, but only the user-supplied pre/poststep routine is called to allow the user to analyze the forecast ensemble.

The general aspects of the filter specific routines `PDAF_assimilate_*` are described on the page [ModifyModelforEnsembleIntegration Modification of the model code for the ensemble integration] and its sub-page on [InsertAnalysisStep inserting the analysis step]. The routine is used in the fully-parallel implementation variant of the data assimilation system. When the 'flexible' implementation variant, the routines `PDAF_put_state_*' are used. 

The interface is the following:
{{{
  SUBROUTINE PDAF_assimilate_prepost_si(status_pdaf)
}}}
with the following arguments:
 * `status_pdaf`: The integer status flag. It is zero, if `PDAF_assimilate_prepostep_si` is exited without errors.

The routine calls two user-supplied call-back routines. They are described, for example, on the page on [ImplementAnalysisestkf implementing the analysis step of the ESTKF algorithm].

It is recommended that the value of `status_pdaf` is checked in the program after `PDAF_assimilate_prepost_si` is executed. Only if its value is 0 the execution was successful.