HP MLIB User's Guide Vol. 2 7th Ed.

Chapter 5 Fast Fourier Transforms 559
Simultaneous one-dimensional FFT CFFTS/ZFFTS
Example 1 Compute the forward DFT of 256 COMPLEX*8 data sets of length 1024. The
data sets are stored as the columns of array Z whose dimensions are 1025 by
256.
INTEGER*4 L,INCL,N,INCN,IOPT,IER
COMPLEX*8 Z(1025,256)
L = 1024
INCL = 1
N = 256
INCN = 1025
IOPT = 1
CALL CFFTS (Z,L,INCL,N,INCN,IOPT,IER)
IF ( IER .NE. 0 ) THEN
handle error condition
END IF
Example 2 Compute the inverse DFT of 1024 COMPLEX*8 data sets of length 256. The
data sets are stored as the rows of array Z whose dimensions are 1025 by 256.
INTEGER*4 L,INCL,N,INCN,IOPT,IER
COMPLEX*8 Z(1025,256)
L = 256
INCL = 1025
N = 1024
INCN = 1
IOPT = -1
CALL CFFTS (Z,L,INCL,N,INCN,IOPT,IER)
IF ( IER .NE. 0 ) THEN
handle error condition
END IF