Introduction

Users can write a subroutine to freely derive (and print or store) quantities of interest from the entire grid. To activate this functionality, set the following in your usr_init routine:

subroutine usr_init()
  ...
  usr_write_analysis => my_analysis
  ...
end subroutine usr_init

Setup in par file

Similar to the other IO-mechanisms, analysis is scheduled within the savelist:

 &savelist;
        dtsave_custom = 0.1 ! Save every 0.1 time units
        ditsave_custom = 10 ! Save every 10 iterations
/

write_analysis subroutine

The user-defined analysis subroutine takes no arguments. It operates on the lowest abstraction level of MPI-AMRVAC so that the user has the flexibility to loop over the the SFC and freely perform integrals over the grid-functions, similar to the printlog_special. A special file-unit is reserved for the IO: unitanalysis. This should be used for any IO performed by this routine.

Example of analysis routine

subroutine my_analysis()
  double precision :: tmp, wmax
  integer          :: iigrid, igrid, ierrmpi
 
  tmp = 0
  do iigrid = 1, igridstail
    igrid = igrids(iigrid)
    tmp = max(tmp, maxval(pw(igrid)%w(ixm^t, rho_)))
  end do
 
  call mpi_allreduce(tmp, wmax, 1, mpi_double_precision, &
       mpi_max, icomm, ierrmpi)
 
  print *, mype, global_time, "maximum density is", wmax
end subroutine my_analysis