Contents
dfft3f - compute the Fourier coefficients of a real periodic
sequence. The DFFT operations are unnormalized, so a call of
DFFT3F followed by a call of DFFT3B will multiply the input
sequence by M*N*K.
SUBROUTINE DFFT3F(PLACE, FULL, M, N, K, A, LDA, B, LDB, WORK, LWORK)
CHARACTER * 1 PLACE, FULL
INTEGER M, N, K, LDA, LDB, LWORK
DOUBLE PRECISION A(LDA,N,*), B(2*LDB,N,*), WORK(*)
SUBROUTINE DFFT3F_64(PLACE, FULL, M, N, K, A, LDA, B, LDB, WORK,
LWORK)
CHARACTER * 1 PLACE, FULL
INTEGER*8 M, N, K, LDA, LDB, LWORK
DOUBLE PRECISION A(LDA,N,*), B(2*LDB,N,*), WORK(*)
F95 INTERFACE
SUBROUTINE FFT3F(PLACE, FULL, [M], [N], [K], A, [LDA], B, [LDB],
WORK, LWORK)
CHARACTER(LEN=1) :: PLACE, FULL
INTEGER :: M, N, K, LDA, LDB, LWORK
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:,:) :: A, B
SUBROUTINE FFT3F_64(PLACE, FULL, [M], [N], [K], A, [LDA], B, [LDB],
WORK, LWORK)
CHARACTER(LEN=1) :: PLACE, FULL
INTEGER(8) :: M, N, K, LDA, LDB, LWORK
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:,:) :: A, B
C INTERFACE
#include <sunperf.h>
void dfft3f(char place, char full, int m, int n, int k, dou-
ble *a, int lda, double *b, int ldb, double *work,
int lwork);
void dfft3f_64(char place, char full, long m, long n, long
k, double *a, long lda, double *b, long ldb, dou-
ble *work, long lwork);
PLACE (input)
Select an in-place ('I' or 'i') or out-of-place
('O' or 'o') transform.
FULL (input)
Select a full ('F' or 'f') or partial (' ')
representation of the results. If the caller
selects full representation then an MxNxK real
array will transform to produce an MxNxK complex
array. If the caller does not select full
representation then an MxNxK real array will
transform to a (M/2+1)xNxK complex array that
takes advantage of the symmetry properties of a
transformed real sequence.
M (input) Integer specifying the number of rows to be
transformed. It is most efficient when M is a
product of small primes. M >= 0; when M = 0, the
subroutine returns immediately without changing
any data.
N (input) Integer specifying the number of columns to be
transformed. It is most efficient when N is a
product of small primes. N >= 0; when N = 0, the
subroutine returns immediately without changing
any data.
K (input) Integer specifying the number of planes to be
transformed. It is most efficient when K is a
product of small primes. K >= 0; when K = 0, the
subroutine returns immediately without changing
any data.
A (input/output)
On entry, a three-dimensional array A(LDA,N,K)
that contains input data to be transformed. On
exit, if an in-place transform is done and FULL is
not 'F' or 'f', A(1:2*(M/2+1),1:N,1:K) will con-
tain the partial transformed results. If FULL =
'F' or 'f', A(1:2*M,1:N,1:K) will contain the com-
plete transformed results.
LDA (input)
Leading dimension of the array containing the data
to be transformed. LDA must be even if the
transformed sequences are to be stored in A.
If PLACE = ('O' or 'o') LDA >= M
If PLACE = ('I' or 'i') LDA must be even. If
FULL = ('F' or 'f'), LDA >= 2*M
FULL is not ('F' or 'f'), LDA >= 2*(M/2+1)
B (input/output)
Upon exit, a three-dimensional array B(2*LDB,N,K)
that contains the transformed results if an out-
of-place transform is done. Otherwise, B is not
used.
If an out-of-place transform is done and FULL is
not 'F' or 'f', B(1:2*(M/2+1),1:N,1:K) will con-
tain the partial transformed results. If FULL =
'F' or 'f', B(1:2*M,1:N,1:K) will contain the com-
plete transformed results.
LDB (input)
2*LDB is the leading dimension of the array B. If
an in-place transform is desired LDB is ignored.
If PLACE is ('O' or 'o') and
FULL is ('F' or 'f'), then LDB >= M
FULL is not ('F' or 'f'), then LDB >= M/2 + 1
Note that even though LDB is used in the argument
list, 2*LDB is the actual leading dimension of B.
WORK (input/output)
One-dimensional real array of length at least
LWORK. WORK must have been initialized by DFFT3I.
LWORK (input)
Integer. LWORK >= (M + 2*(N + K) + 4*K + 45).