= PDAF_put_state_seek = This page documents the routine `PDAF_put_state_seek` of PDAF. The routine is typically called in `assimilate_pdaf` or directly in the model code. The routines `PDAF_put_state_*` are 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 when using the SEEK filter is the following: {{{ SUBROUTINE PDAF_put_state_seek(U_collect_state, U_init_dim_obs, U_obs_op, & U_init_obs, U_prepoststep, U_prodRinvA, status_pdaf) }}} with the following arguments: * `U_collect_state`: 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 `PDAF_get_state`. * `U_init_dim_obs`: The name of the user-supplied routine that provides the size of observation vector * `U_obs_op`: The name of the user-supplied routine that acts as the observation operator on some state vector * `U_init_obs`: The name of the user-supplied routine that initializes the vector of observations * `U_prepoststep`: The name of the pre/poststep routine as in `PDAF_get_state` * `U_prodRinvA`: The name of the user-supplied routine that computes the product of the inverse of the observation error covariance matrix with some matrix provided to the routine by PDAF. This operation occurs during the analysis step of the SEEK filter. * `status`: The integer status flag. It is zero, if `PDAF_assimilate_seek` is exited without errors. The user-supplied call-back routines are described on the page on [ImplementAnalysisseek implementing the analysis step of the SEEK filter]. It is recommended that the value of `status_pdaf` is checked in the program after PDAF_put_state_seek is executed. Only if its value is 0 the initialization was successful. PDAF also has a [PdafSimplifiedInterface Simplified Interface] providing the routine `PDAF_put_state_seek_si`. In the simplified interface, the name of the user-supplied routines have predefined names and do not appear in the call to `PDAF_put_state_seek_si`. More information on the pre-defined names is provided in the [ImplementAnalysisseek page on implementing the analysis step of the SEEK filter].