| 55 |  | The purpose of `assimilate_pdaf` is to call the filter-specific PDAF-core routine `PDAF_assimilate_X`, with `X` being the name of the filter method. It is also possible to insert the call to `PDAF_assimilate_X` directly into the model code. However, using the additional interface routine yield usually cleaner source code. This is because of subroutine name that are specified in the call the `PDAF_assimilate_X` or when more than one filter are implemented. | 
          
            |  | 55 | The purpose of `assimilate_pdaf` is to call the filter-specific PDAF-core routine `PDAF_assimilate_X`, with `X` being the name of the filter method. It is also possible to insert the call to `PDAF_assimilate_X` directly into the model code. However, using the additional interface routine yield usually cleaner source code. This is because of subroutine names that are specified in the call the `PDAF_assimilate_X` or when more than one filter are implemented. | 
          
            |  | 56 |  | 
          
            |  | 57 | One has to ensure that `PDAF_assimilate_X` is called at each time step, so that PDAF can count the time steps until the next analysis time. |