SEQUENCE D'APPEL...
       smspec  IN OUT [ FILTER ] INPUT OUTPUT [ -a VAL1 -b VAL2 -b VAL3 -d VAL4 ]
 
 
      AUTHOR  - B.DENIS, DECEMBER 1999.
      LAST REVISION: $Header: /home/cvs/RMNLIB/utils/rdiag/lspgm/smspec.ptn,v 4.6 2014/10/16 11:37:06 dugas Exp $
 
 
      DESCRIPTION...
       smspec - SPECTRAL FILTERING USING DISCREET SIN AND COS TRANSFORMS.
 
 
      INPUT FILE...
       IN     = INPUT ARRAY FILE
 
      OUTPUT FILES...
       OUT    = FILTERED ARRAY FILE
       FILTER = THE ACTUAL FILTER ARRAY (OPTIONAL)
 
 
      PARAMETERS...
       CAS (a) = TYPE OF (SUPPORTED) TRANSFORMS.
                 3 => SIN SHIFTED ONLY.
                 4 => COS SHIFTED ONLY.
                 5 => REGULAR SIN & COS (DEFAULT)
       WXL (b) = LONG WAVELENGTH CUTOFF (DEFAULT=1.E-20)
                 INFORMATION WITH WAVELENGTH LONGER OR EQUAL TO WXL WILL
                 BE PRESERVE.
       WXS (c) = SHORT WAVELENGTH CUTOFF (DEFAULT=1.E-20)
                 INFORMATION WITH WAVELENGTH SMALLER OR EQUAL THAN WXL WILL
                 BE REMOVED.
       DX  (d) = GRID SPACING IN KILOMETERS (DEFAULT=1)
 
 
       Notes: 1) If WXL = WXS, then wavelength smaller (not equal) than WXL
                 will be removed. WXL must always be .GE. than WXS.
              2) The filter function is equal to "1" at WXL and to "0" at WXS.
                 In between it follows a "COS(WAVENUMBER)**2" function.
              3) As of now, grids have to be of even-sized dimensions.
 
                ^    FILTER FUNCTION (RESPONSE)
                |
             1 -| ----
                |     \
                |      \
                |       \
                |        \
                |         \
                |          \
             0 -|-----|-----|------ SHORTEST-WAVES -->
                     WXL   WXS
 
 
       READ(5,5000) CAS,WXL,WXS,DX
 5000  FORMAT(10X,I5,3E10.0)
 
 
      EXAMPLE OF INPUT CARD...
 
  SMSPEC      4      1000       500        45
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 CAS PARAMETRE NOT VALID
        2 WXS AND/OR WXL INCORRECT
        3 DX IS SMALLER THAN 0
        4 PROBLEMS READING FILE IN
        5 FOUND UN-EVEN GRID SIZES
        6 PROBLEMS READING INPUT PARAMETRES
        7 MORE THAN ONE ARRAY SIZE