= PDAF_put_state_ensrf = 

This page documents the routine `PDAF_put_state_ensrf` of PDAF. The routine is used to execute the ENSRF/EAKF filters, which were added to PDAF with version 3.0. 

The routine is typically called in `assimilate_pdaf` or directly in the model code. For newer implementations we recommend to use the generic interface routine [wiki:PDAF3_put_state_local] since less user-supplied call-back routines are required with the PDAF3 interface.  

The routines `PDAF_put_state_*` are used for the offline mode of PDAF and can be used with the 'flexible' implementation variant of PDAF. 
The general aspects of the filter specific routines `PDAF_put_state_*` 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]. For the 'fully parallel' implementation variant, the alternative routines `PDAF_assimilate_*` are used.

The interface for using the ENSRF/EAKF is the following:
{{{
SUBROUTINE PDAF_put_state_ensrf(U_collect_state, &
     U_init_dim_obs, U_obs_op,  U_init_obs, U_init_obsvars, &
     U_localize_covar_serial, &
     U_prepoststep, outflag)
}}}
with the following arguments:
 * `U_collect_state`: [[BR]]The name of the user-supplied routine that initializes a state vector from the array holding the ensemble of model states from the model fields. This is basically the inverse operation to `U_distribute_state` used in [wiki:PDAF_get_state].
 * `U_init_dim_obs`: [[BR]]The name of the user-supplied routine that provides the size of observation vector
 * `U_obs_op`: [[BR]]The name of the user-supplied routine that acts as the observation operator on some state vector
 * `U_init_obs`: [[BR]]The name of the user-supplied routine that initializes the vector of observations
 * `U_init_obsvars`: [[BR]]The name of the user-supplied routine that initializes the vector of observation error variances.
 * `U_localize_covar_serial`: [[BR]]The name of the user-suppplied routine that applies the covariance localization for a single observation
 * `U_prepoststep`: [[BR]]The name of the user-supplied pre/poststep routine as in `PDAF_get_state`
 * `status_pdaf`: [[BR]]The integer status flag. It is zero, if the routine is exited without errors. 

The user-supplied call-back routines are described on the page on [wiki:ImplementAnalysisENSRF_EAKF implementing the analysis step of the ENSRF/EAKF]. Here also the possible choices of `subtype` are explained. These select the particular filter variant.

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