CALL SEQUENCE...
       flat  IN OUT INPUT OUTPUT [ -a VAL -b VAL2 -c VAL3 -d VAL4 ]
 
 
      AUTHORS - B. Denis, mars 2001.
      LAST REVISION: $Header: /home/cvs/RMNLIB/utils/rdiag/lspgm/flat.ptn,v 4.6 2014/09/25 20:20:47 dugas Exp $
 
 
      DESCRIPTION...
       FLAT -  FLATTEN THE LATERAL BOUNDARY IN THE NORMAL DIRECTION.
 
 
      PURPOSE - APPLY A SMOOTHING OVER A ZONE (TO BE DEFINED BELOW)
                ALONG THE LATERAL BOUNDARY. THE SMOOTHING IS DONE IN
                THE DIRECTION NORMAL TO THE BOUNDARY.
 
 
      INPUT FILE...
        IN = INPUT FILE ON INITIAL GRID
 
      OUTPUT FILE...
        OUT = OUTPUT FILE ON OUTPUT GRID
 
 
      INPUT PARAMETERS...
        NBG (a) = NB OF GRIDPOINT FLATTEN ON THE LEFT BOUNDARY
        NBD (b) = NB OF GRIDPOINT FLATTEN ON THE RIGHT BOUNDARY
        NBB (c) = NB OF GRIDPOINT FLATTEN ON THE LOWER BOUNDARY
        NBH (d) = NB OF GRIDPOINT FLATTEN ON THE UPPER BOUNDARY
 
       READ(5,5000) NBG,NBD,NBB,NBH
 5000  FORMAT(10X,4I5)
 
 
      EXAMPLE OF INPUT CARD...
 
 FLAT         3    3    3    3
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 UNABLE TO REAL FIRST GRID OR SUBA ARRAY
        2 RATIO NBG/NI DANGEROUSLY HIGH
        3 RATIO NBD/NI DANGEROUSLY HIGH
        4 RATIO NBB/NI DANGEROUSLY HIGH
        5 RATIO NBH/NI DANGEROUSLY HIGH
        6 ERROR READING INPUT PARAMETERS
        7 PREMATURE EOF ON FILE IN