SPGRADX

The SPGRADX routine computes the x-gradient of fields
            in complex Fourier space.
            The x-gradient of a vector field W is:
              WX=CONJG(W)*L/RERTH
            where l is the wavenumber and rerth is the earth radius,
            So that the result is the x-gradient of the pseudo-vector.
            The x-gradient of a scalar field W is:
              WX=CONJG(W)*L/(RERTH*CLAT)
            Where clat is the cosine of latitude.
            At the pole this is undefined, so the way to get
            The x-gradient at the pole is by passing both
            The weighted wavenumber 0 and the unweighted wavenumber 1
            amplitudes at the pole and setting MP=10.
            In this case, the wavenumber 1 amplitudes are used
            to compute the x-gradient and then zeroed out.

   Input argument list:
      M        - INTEGER FOURIER WAVENUMBER TRUNCATION
      INCW     - INTEGER FIRST DIMENSION OF THE COMPLEX AMPLITUDE ARRAY
                 (INCW >= M+1)
      KMAX     - INTEGER NUMBER OF FOURIER FIELDS
      MP       - INTEGER (KM) IDENTIFIERS
                 (0 OR 10 FOR SCALAR, 1 FOR VECTOR)
      CLAT     - REAL COSINE OF LATITUDE
      W        - COMPLEX(INCW,KMAX) FOURIER AMPLITUDES
 
   Output argument list:
      W        - COMPLEX(INCW,KMAX) FOURIER AMPLITUDES
                 CORRECTED WHEN MP=10 AND CLAT=0
      WX       - COMPLEX(INCW,KMAX) COMPLEX AMPLITUDES OF X-GRADIENTS
 
 


  
SPLIB.tar
  
Library contains routines to be
   be used for a variety of spectral transform functions. (Fortran90) 

   Date posted: 2/23/2007