CALL SEQUENCE...
       zxwave  MEAN AMPS PHASES INPUT OUTPUT [ -lat VAL1 -m VAL2 ]
 
 
      DESCRIPTION...
       zxwave - MAKES CROSS-SECTION OF SPECTRAL AMPLITUDE AND PHASE
 
 
      AUTHOR  - S.Lambert, MAY 14/83.
      LAST REVISION: $Header: /home/cvs/RMNLIB/utils/rdiag/lspgm/zxwave.ptn,v 4.11 2014/10/16 11:34:10 dugas Exp $
 
 
      PURPOSE - COMPUTES CROSS-SECTIONS OF THE AMPLITUDES AND PHASES FOR A
                ZONAL WAVENUMBER DECOMPOSITION OF FIELD X.
 
      NOTES   - 1) CROSS-SECTIONS ARE PRODUCED FOR WAVENUMBERS UP TO A
                   GIVEN MAX. 
                2) INPUT IS SPHERICAL HARMONIC COEFFICIENTS FOR NLEV
                   PRESSURE LEVELS.
                3) MAXIMUM DIMENSIONS:  999 WAVES, 999 LATS AND 999 LEVS.
 
 
      INPUT FILE...
       MEAN   = GLOBAL SPECTRAL FIELDS
 
      OUTPUT FILES...
       AMPS   = AMPLITUDE CROSS-SECTIONS
       PHASES = PHASE     CROSS-SECTIONS
 
 
      INPUT PARAMETERS...
 
       NLAT (lat) = NUMBER OF LATITUDES IN THE CROSS-SECTION
       M    (m)   = MAXIMUM ZONAL WAVENUMBER.
 
       READ( 5,5000 ) NLAT,M
 5000  FORMAT(10X,2I5)
      EXAMPLE...
 
    ZXWAVE   52    6
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 REQUESTED NUMBER OF LATITUDES TOO LARGE
        2 REQUESTED NUMBER OF WAVES TOO LARGE
        3 PROBLEMS READING SPECTRAL FILE MEAN
        4 FILE MEAN IS NOT OF SPECTRAL TYPE
        5 NOT ENOUGH WAVES IN MEAN ARRAYS
        6 ABORT ERROR READING FILE MEAN
        7 ABORT ERROR READIND INPUT DIRECTIVES