Case 1A: Check of the Line Absorption Implementation.

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The aim of this case is to check the correct model implementation for
line absorption calculation. Line-by-line calculations will be carried
out for a set of selected species and for given frequencies. In order
to avoid the inconsistency due to variations in input parameters, full
spectroscopic data, polynomial coefficients used to compute the
partition function, and the isotopic ratio for each isotope of each
target species are delivered. For the given specifications the
participants should compute the absorption coefficients for given
pressure/altitude levels.

Input - Output Files
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 Format:
 ========
  The files (except the spectroscopic data file) are ASCII, in
  ARTS format.  
  They can easily be recognized by the extension 'aa'.
  The file can start with an arbitrary number of comment lines.  
  These lines starts with the hash symbol (#) 
  The first row after the comment lines give the number of matrices 
  in the array. After this follows, for each matrix, a row giving 
  the matrix size followed by the data in row order.

 Input: 
 =======
-  KeySpecies_case1A.txt -->> a text file which gives the set of the
   target species for which the absorption coefficients should be calculated.
 - atm_scenario_case1A.aa -->> profiles of temperature,
   altitude, pressure, and trace gas volume mixing ratios. The data is
   display in ARTS format. See the header of the file for a more
   detailed description.
 - Freq_mono_case1A.aa-->> frequency values for which the calculation
   should be performed.
 - Spectro_data_case1A.dat -->> spectroscopic data for the key
   species. The data is displayed in HITRAN format. 
 - FuncPartition_IsotopicRatio.txt: a text file which gives the 4 polynomial
   coefficients for the calculation of partition functions 
   (a + b*T + c*T^2 + d*T3), and isotopic ratios for each 
   isotope of each given species.      
 - line shape : Voigt (Lorenz if Voigt is not available), no cutoff
    -->> the line shape for the calculation.
 - p_z_abs_case1A.aa -->> a 2 column matrix giving the pressure and
   the altitude grid for the output of the absorption coefficients. 
   The first column contains the levels in pressure units [Pa], while the 
   second column contains the corresponding levels in geometric altitude 
   units [m]. 

Output: 
========  
 
  - absorption coefficients on the grid given in
  p_z_abs_case1A.aa. The output file should be in ARTS format. Each data
  row will give the absorption coefficients for the given frequencies,
  at one pressure/altitude level.