SPFFT

The SPFFT routine performs multiple fast fourier transforms
          between complex amplitudes in Fourier space and real values
          in cyclic physical space.
          Subprogram SPFFT must be invoked first with idir=0
          to initialize trigonemetric data.  Use subprogram SPFFT1
          to perform an FFT without previous initialization.
          This version invokes the IBM ESSL FFT.

USAGE:    CALL SPFFT(IMAX,INCW,INCG,KMAX,W,G,IDIR)

   Input argument list:
      IMAX     - INTEGER NUMBER OF VALUES IN THE CYCLIC PHYSICAL SPACE
                 (SEE LIMITATIONS ON IMAX IN REMARKS BELOW.)
      INCW     - INTEGER FIRST DIMENSION OF THE COMPLEX AMPLITUDE ARRAY
                 (INCW >= IMAX/2+1)
      INCG     - INTEGER FIRST DIMENSION OF THE REAL VALUE ARRAY
                 (INCG >= IMAX)
      KMAX     - INTEGER NUMBER OF TRANSFORMS TO PERFORM
      W        - COMPLEX(INCW,KMAX) COMPLEX AMPLITUDES IF IDIR>0
      G        - REAL(INCG,KMAX) REAL VALUES IF IDIR<0
      IDIR     - INTEGER DIRECTION FLAG
                 IDIR=0 TO INITIALIZE INTERNAL TRIGONOMETRIC DATA
                 IDIR>0 TO TRANSFORM FROM FOURIER TO PHYSICAL SPACE
                 IDIR<0 TO TRANSFORM FROM PHYSICAL TO FOURIER SPACE
 
   Output argument list:
      W        - COMPLEX(INCW,KMAX) COMPLEX AMPLITUDES IF IDIR<0
      G        - REAL(INCG,KMAX) REAL VALUES IF IDIR>0

 


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

   Date posted: 2/23/2007