= PDAF_alloc =

This page documents the routine `PDAF_alloc` which is part of the module `PDAF_utils`. 

`PDAF_alloc` is used by each DA method in its routine `PDAF_X_alloc` to allocate the arrays provided by PDAF's framework infrastructure.

The interface is:
{{{
SUBROUTINE PDAF_alloc(dim_p, dim_ens, dim_ens_task, dim_es, dim_bias_p, &
     dim_lag, statetask, outflag)

  INTEGER, INTENT(in) :: dim_p           !< Size of state vector
  INTEGER, INTENT(in) :: dim_ens         !< Ensemble size
  INTEGER, INTENT(in) :: dim_ens_task    !< Ensemble size handled by a model task
  INTEGER, INTENT(in) :: dim_es          !< Dimension of error space (size of Ainv)
  INTEGER, INTENT(in) :: dim_bias_p      !< Size of bias vector
  INTEGER, INTENT(in) :: dim_lag         !< Smoother lag
  INTEGER, INTENT(in) :: statetask       !< ID of model task forecasting a single state
  INTEGER, INTENT(inout):: outflag       !< Status flag

}}}

Notes:
* For consistency, PDAF's internal arrays are always allocated, but if they are not used they are allocated with minimum size
 * If `dim_es=0`, the array `Ainv` will be allocated with size `(1,1)`
 * If `dim_bias_p=0`, the array `bias` will be allocated with size `(1)`
 * If `dim_lag=0`, the array `sens` will be allocated with size `(1,1,1)`
* The dimensions are usually set in `PDAF_X_init` and then used in `PDAF_X_alloc`.