= PDAF_gather_dim_obs_f = 

This page documents the routine `PDAF_gather_dim_obs_f` of PDAF, which was introduced with PDAF V1.13.

In the local filters (LESKTF, LETKF, LSEIK, LNETF) this routine gathers the total observation dimension from process-local observation dimensions and returns this dimension.

The routine has to be called once before using any of the routines [wiki:PDAF_gather_obs_f] or [wiki:PDAF_gather_obs_f2]. This is because it stores the information on the process-local observation dimensions to enable the gathering operations in the two other routines.


The routine is typically used in the routine [wiki:init_dim_obs_f_pdaf] if the analysis step of the local filters is parallelized.

The interface is the following:
{{{
  SUBROUTINE PDAF_gather_dim_obs_f(dim_obs_p, dim_obs_f)
}}}
with the following arguments:
 * `dim_obs_p` : `integer, intent(in)`[[BR]] Process-local dimension of observation vector
 * `dim_obs_f` : `integer, intent(out)`[[BR]] Full dimension of observation vector

Notes:
 * It is allowed to compute `PDAF_gather_dim_obs_f` multiple times. However, the calls to `PDAF_gather_obs_f` and `PDAF_gather_obs_f2` will use the dimensions defined in the most recent call to `PDAF_gather_dim_obs_f`