zfftzm(3P) Sun Performance Library zfftzm(3P)NAMEzfftzm - initialize the trigonometric weight and factor tables or com‐
pute the one-dimensional Fast Fourier Transform (forward or inverse) of
a set of data sequences stored in a two-dimensional double complex
array.
SYNOPSIS
SUBROUTINE ZFFTZM(IOPT, N1, N2, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR)
INTEGER IOPT, N1, N2, LDX, LDY, IFAC(*), LWORK, IERR
DOUBLE COMPLEX X(LDX, *), Y(LDY, *)
DOUBLE PRECISION SCALE, TRIGS(*), WORK(*)
SUBROUTINE ZFFTZM_64(IOPT, N1, N2, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR)
INTEGER*8 IOPT, N1, N2, LDX, LDY, IFAC(*), LWORK, IERR
DOUBLE PRECISION SCALE, TRIGS(*), WORK(*)
DOUBLE COMPLEX X(LDX, *), Y(LDY, *)
F95 INTERFACE
SUBROUTINE FFTM(IOPT, [N1], [N2], [SCALE], X, [LDX], Y, [LDY], TRIGS,
IFAC, WORK, [LWORK], IERR)
INTEGER, INTENT(IN) :: IOPT
INTEGER, INTENT(IN), OPTIONAL :: N1, N2, LDX, LDY, LWORK
REAL(8), INTENT(IN), OPTIONAL :: SCALE
COMPLEX(8), INTENT(IN), DIMENSION(:,:) :: X
COMPLEX(8), INTENT(OUT), DIMENSION(:,:) :: Y
REAL(8), INTENT(INOUT), DIMENSION(:) :: TRIGS
INTEGER, INTENT(INOUT), DIMENSION(:) :: IFAC
REAL(8), INTENT(OUT), DIMENSION(:) :: WORK
INTEGER, INTENT(OUT) :: IERR
SUBROUTINE FFTM_64(IOPT, [N1], [N2], [SCALE], X, [LDX], Y, [LDY], TRIGS, IFAC, WORK, [LWORK], IERR)
INTEGER(8), INTENT(IN) :: IOPT
INTEGER(8), INTENT(IN), OPTIONAL :: N1, N2, LDX, LDY, LWORK
REAL(8), INTENT(IN), OPTIONAL :: SCALE
COMPLEX(8), INTENT(IN), DIMENSION(:,:) :: X
COMPLEX(8), INTENT(OUT), DIMENSION(:,:) :: Y
REAL(8), INTENT(INOUT), DIMENSION(:) :: TRIGS
INTEGER(8), INTENT(INOUT), DIMENSION(:) :: IFAC
REAL(8), INTENT(OUT), DIMENSION(:) :: WORK
INTEGER(8), INTENT(OUT) :: IERR
C INTERFACE
#include <sunperf.h>
void zfftzm_ (int *iopt, int *m, int *n, double *scale, doublecomplex
*x, int *ldx, doublecomplex *y, int *ldy, double *trigs, int
*ifac, double *work, int *lwork, int *ierr);
void zfftzm_64_ (long *iopt, long *m, long *n, double *scale, double‐
complex *x, long *ldx, doublecomplex *y, long *ldy, double
*trigs, long *ifac, double *work, long *lwork, long *ierr);
PURPOSEzfftzm initializes the trigonometric weight and factor tables or com‐
putes the one-dimensional Fast Fourier Transform (forward or inverse)
of a set of data sequences stored in a two-dimensional double complex
array:
N1-1
Y(k,l) = SUM W*X(j,l)
j=0
where
k ranges from 0 to N1-1 and l ranges from 0 to N2-1
i = sqrt(-1)
isign = 1 for inverse transform or -1 for forward transform
W = exp(isign*i*j*k*2*pi/N1)
ARGUMENTS
IOPT (input)
Integer specifying the operation to be performed:
IOPT = 0 computes the trigonometric weight table and factor
table
IOPT = -1 computes forward FFT
IOPT = +1 computes inverse FFT
N1 (input)
Integer specifying length of the input sequences. N1 is most
efficient when it is a product of small primes. N1 >= 0.
Unchanged on exit.
N2 (input)
Integer specifying number of input sequences. N2 >= 0.
Unchanged on exit.
SCALE (input)
Double precision scalar by which transform results are
scaled. Unchanged on exit. SCALE is defaulted to 1.0D0 for
F95 INTERFACE.
X (input) X is a double complex array of dimensions (LDX, N2) that con‐
tains the sequences to be transformed stored in its columns.
LDX (input)
Leading dimension of X. LDX >= N1 Unchanged on exit.
Y (output)
Y is a double complex array of dimensions (LDY, N2) that con‐
tains the transform results of the input sequences. X and Y
can be the same array starting at the same memory location,
in which case the input sequences are overwritten by their
transform results. Otherwise, it is assumed that there is no
overlap between X and Y in memory.
LDY (input)
Leading dimension of Y. If X and Y are the same array, LDY =
LDX Else LDY >= N1 Unchanged on exit.
TRIGS (input/output)
Double precision array of length 2*N1 that contains the
trigonometric weights. The weights are computed when the
routine is called with IOPT = 0 and they are used in subse‐
quent calls when IOPT = 1 or IOPT = -1. Unchanged on exit.
IFAC (input/output)
Integer array of dimension at least 128 that contains the
factors of N1. The factors are computed when the routine is
called with IOPT = 0 and they are used in subsequent calls
when IOPT = 1 or IOPT = -1. Unchanged on exit.
WORK (workspace)
Double precision array of dimension at least 2*N1*NCPUS where
NCPUS is the number of threads used to execute the routine.
The user can also choose to have the routine allocate its own
workspace (see LWORK).
LWORK (input)
Integer specifying workspace size. If LWORK = 0, the routine
will allocate its own workspace.
IERR (output)
On exit, integer IERR has one of the following values:
0 = normal return
-1 = IOPT is not 0, 1 or -1
-2 = N1 < 0
-3 = N2 < 0
-4 = (LDX < N1)
-5 = (LDY < N1) or (LDY not equal LDX when X and Y are same
array)
-6 = (LWORK not equal 0) and (LWORK < 2*N1*NCPUS)
-7 = memory allocation failed
SEE ALSO
fft
6 Mar 2009 zfftzm(3P)
