Contents
cfftcm - initialize the trigonometric weight and factor
tables or compute the one-dimensional Fast Fourier Transform
(forward or inverse) of a set of data sequences stored in a
two-dimensional complex array.
SUBROUTINE CFFTCM(IOPT, N1, N2, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR)
INTEGER IOPT, N1, N2, LDX, LDY, IFAC(*), LWORK, IERR
COMPLEX X(LDX, *), Y(LDY, *)
REAL SCALE, TRIGS(*), WORK(*)
SUBROUTINE CFFTCM_64(IOPT, N1, N2, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR)
INTEGER*8 IOPT, N1, N2, LDX, LDY, IFAC(*), LWORK, IERR
REAL SCALE, TRIGS(*), WORK(*)
COMPLEX X(LDX, *), Y(LDY, *)
F95 INTERFACE
SUBROUTINE FFTM(IOPT, [N1], [N2], [SCALE], X, [LDX], Y, [LDY], TRIGS,
IFAC, WORK, [LWORK], IERR)
INTEGER*4, INTENT(IN) :: IOPT
INTEGER*4, INTENT(IN), OPTIONAL :: N1, N2, LDX, LDY, LWORK
REAL, INTENT(IN), OPTIONAL :: SCALE
COMPLEX, INTENT(IN), DIMENSION(:,:) :: X
COMPLEX, INTENT(OUT), DIMENSION(:,:) :: Y
REAL, INTENT(INOUT), DIMENSION(:) :: TRIGS
INTEGER*4, INTENT(INOUT), DIMENSION(:) :: IFAC
REAL, INTENT(OUT), DIMENSION(:) :: WORK
INTEGER*4, 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, INTENT(IN), OPTIONAL :: SCALE
COMPLEX, INTENT(IN), DIMENSION(:,:) :: X
COMPLEX, INTENT(OUT), DIMENSION(:,:) :: Y
REAL, INTENT(INOUT), DIMENSION(:) :: TRIGS
INTEGER(8), INTENT(INOUT), DIMENSION(:) :: IFAC
REAL, INTENT(OUT), DIMENSION(:) :: WORK
INTEGER(8), INTENT(OUT) :: IERR
C INTERFACE
#include <sunperf.h>
void cfftcm_ (int *iopt, int *n1, int *n2, float *scale,
complex *x, int *ldx, complex *y, int *ldy, float
*trigs, int *ifac, float *work, int *lwork, int
*ierr);
void cfftcm_64_ (long *iopt, long *n1, long *n2, float
*scale, complex *x, long *ldx, complex *y, long
*ldy, float *trigs, long *ifac, float *work, long
*lwork, long *ierr);
cfftcm initializes the trigonometric weight and factor
tables or computes the one-dimensional Fast Fourier
Transform (forward or inverse) of a set of data sequences
stored in a two-dimensional 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)
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)
Real scalar by which transform results are scaled.
Unchanged on exit. SCALE is defaulted to 1.0 for
F95 INTERFACE.
X (input) X is a complex array of dimensions (LDX, N2) that
contains 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 complex array of dimensions (LDY, N2) that
contains 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)
Real array of length 2*N1 that contains the tri-
gonometric weights. The weights 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.
IFAC (input/output)
Integer array of dimension at least 128 that con-
tains 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)
Real 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
fft