%------------------------------------------------------------------------
% NAME:     qp_abs
%
%           A function to calculate the absorption corresponding to a Q 
%           structure, with the possibility to replace F_MONO and P_ABS. 
%
%           The optional arguments F_MONO and P_ABS can be empty, and
%           then original vectors are used.
%
%           Not all fields of Q must be set. 
%
% FORMAT:   y = qp_ympb( Q [, f_mono, p_abs ] )
%
% OUT:      Abs            Calculated absorption.
% IN:       Q              Setting structure.
% OPTIONAL: f_mono         Alternative monochromatic frequency grid.
%           p_abs          Alternative absorption pressure grid.
% TEMPLATE: basic.tmplt
%------------------------------------------------------------------------

% HISTORY: 2002.01.17  Created by Patrick Eriksson.


function Abs = qp_abs( Q, f_mono, p_abs )


%=== Create temporary dir
%
tmpdir    = temporary_directory( Q.TMP_AREA );


%=== If necessary, use TMPDIR as CALCGRIDS_DIR
%
if nargin > 1
  %
  %= Copy all .aa and .ab files to TMPDIR
  D = dir( [Q.CALCGRIDS_DIR,'/*.a*'] );
  for i = 1:length(D)
    copyfile( [Q.CALCGRIDS_DIR,'/',D(i).name], [tmpdir,'/',D(i).name] ); 
  end
  %
  Q.CALCGRIDS_DIR = tmpdir;
  %
  if exist('f_mono') & ~isempty(f_mono)
    write_datafile( [Q.CALCGRIDS_DIR,'/',Q.F_MONO], f_mono, 'VECTOR' );
  end
  %
  if exist('p_abs') & ~isempty(p_abs)
    write_datafile( [Q.CALCGRIDS_DIR,'/',Q.P_ABS], p_abs, 'VECTOR' );
  end
end


%=== Get full path of template file and create cfile
%
template = which( 'basic.tmplt' );
%
QE.ABS_SAVE = 1;
QE.ABS_EXIT = 1;
%
[cfile,basename] = qtool( Q, tmpdir, template, QE );



%=== Run ARTS
%
qp_arts( Q, cfile );



%=== Load spectrum
%
Abs = read_artsvar( basename, 'abs' );


%=== Delete the temporary directory
delete_tmp_dir( Q.TMP_AREA, tmpdir );