dfft3f(3P) Sun Performance Library dfft3f(3P)NAMEdfft3f - 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.
SYNOPSIS
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, double *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, double *work, long lwork);
ARGUMENTS
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 com‐
plex array. If the caller does not select full representa‐
tion 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 trans‐
form is done and FULL is not 'F' or 'f',
A(1:2*(M/2+1),1:N,1:K) will contain the partial transformed
results. If FULL = 'F' or 'f', A(1:2*M,1:N,1:K) will contain
the complete 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 con‐
tains 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 contain the partial trans‐
formed results. If FULL = 'F' or 'f', B(1:2*M,1:N,1:K) will
contain the complete 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).
6 Mar 2009 dfft3f(3P)
