CALL SEQUENCE...
       ggtrig  GGIN GGOUT INPUT OUTPUT [-a VAL1 -kind VAL2 [VAL3] -b VAL4 [-lon]]
 
 
      DESCRIPTION...
       ggtrig - GRID SET MULTIPLIED BY CONST*TRIG(LAT)**N OR CONST*TRIG(N*LON)
 
 
      AUTHOR  - J.D.Henderson, MAY 25/81.
      LAST REVISION: $Header: Corrections-mineures-de-TIMAVG-FSTMDIAG-et-GGTRIG @ 2017-08-15 15:52:24 -0400 (dugas) $
 
 
      PURPOSE - MULTIPLIES ANY 'A','B','G' 'L','N','S' OR 'Z' GRID
                FILE BY CONST*TRIG(LAT)**N OR CONST*TRIG(N*LON),
                WHERE TRIG CAN BE EITHER OF THE FOLLOWING:
                1) ANY OF THE USUAL SINUS, COSINUS
                   OR TANGENT FUNCTIONS.
                2) THE IDENTITY FUNCTION.
 
 
      INPUT FILE...
       GGIN  = 'A','B','G','L','N','S' OR 'Z' GRIDS
 
      OUTPUT FILE...
       GGOUT = GGIN MULTIPLIED AS REQUESTED.
 
 
      INPUT PARAMETERS...
 
       CONST (a)    = MULTIPLYING CONSTANT. BLANK INPUT DEFAULT IS 1.0
       KTR   (kind) = 'SIN', 'COS', 'TAN' OR 'IDF'. THE DEFAULT IS 'COS'
                      AND 'IDF' STANDS FOR IDENTITY FUNCTION
       GEOGR (kind2)= 'ROT' or 'GEO' (the default is 'GEO')
                      Stands for GEOGraphical frame of Reference.
                      This option can only applied to 'Z' grids.
       N     (b)    = INTEGER POWER TO WHICH TRIG FUNCTION IS RAISED
                      IF LON IS NULL. OTHERWISE, LONGITUDE WAVE NUMBER.
                      THE BLANK INPUT DEFAULT IS SET TO 1
       LON          = 0 (DEFAULT) ==> APPLIES TRIG(LAT)**N
                    = ANYTHING ELSE ==> APPLIES TRIG(N*LON)
 
      NOTES:  1) 'G' GRIDS ARE CLASSICAL GAUSSIAN GRIDS; 'A' GRIDS ARE
                 GLOBAL OR HEMISPHERIC LAT-LON GRIDS THAT INCLUDE NEITHER
                 THE POLES OR THE EQUATOR. THEIR FIRST LATITUDE POINT STARTS
                 HALF AN INTERVAL FROM THE POLE. 'B' GRIDS ARE AS A GRIDS,
                 EXCEPT THAT THEY INCLUDE POLES AND MAY ALSO INCLUDE THE
                 EQUATOR WHEN THERE IS AN UNEVEN NUMBER OF LATITUDES.
                 THE 'Z' GRID FORMAT IS USED BY THE RPN/CMC GEM MODEL.
              2) For rotated 'Z' grids, it is possible to use the
                 latitudes and longitudes in the rotated or non-rotated
                 geographical frame of reference using the GEOGR parameter.
              3) NEGATIVE EXPONENT OPERATIONS ON 'B' OR 'Z' GRIDS ARE
                 NOT SUPPORTED, AS THEY MAY IMPLY DIVISION BY ZERO
                 AT THE EQUATOR AND THE POLES. FOR THE SAME REASON,
                 TAN(LAT) OPERATIONS ARE NOT SUPPORTED FOR 'B' GRIDS.
 
       READ( 5,5010 ) CONST,KTR,N,LON
 5010  FORMAT(10X,E10.0,2X,A3,2I5)
 
 
      EXAMPLE OF INPUT CARD...
 
    GGTRIG      1.E0  COS    2    0
 
         0123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7
 
 
      EXIT CONDITIONS...
        0 NO PROBLEMS
        1 KTR IS NEITHER SIN,COS OR TAN
        2 ABORT ERROR READING GGIN
        3 ABORT ERROR READIND INPUT DIRECTIVES
        4 UNSUPPORTED GRID TYPE
        5 UNSUPPORTED OPERATION/"GRID TYPE" COMBINATION