Contents
zfft2b - compute a periodic sequence from its Fourier coef-
ficients. The FFT operations are unnormalized, so a call of
ZFFT2F followed by a call of ZFFT2B will multiply the input
sequence by M*N.
SUBROUTINE ZFFT2B(M, N, A, LDA, WORK, LWORK)
DOUBLE COMPLEX A(LDA,*)
INTEGER M, N, LDA, LWORK
DOUBLE PRECISION WORK(*)
SUBROUTINE ZFFT2B_64(M, N, A, LDA, WORK, LWORK)
DOUBLE COMPLEX A(LDA,*)
INTEGER*8 M, N, LDA, LWORK
DOUBLE PRECISION WORK(*)
F95 INTERFACE
SUBROUTINE FFT2B([M], [N], A, [LDA], WORK, LWORK)
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER :: M, N, LDA, LWORK
REAL(8), DIMENSION(:) :: WORK
SUBROUTINE FFT2B_64([M], [N], A, [LDA], WORK, LWORK)
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER(8) :: M, N, LDA, LWORK
REAL(8), DIMENSION(:) :: WORK
C INTERFACE
#include <sunperf.h>
void zfft2b(int m, int n, doublecomplex *a, int lda, double
*work, int lwork);
void zfft2b_64(long m, long n, doublecomplex *a, long lda,
double *work, long lwork);
M (input) Number of rows to be transformed. These subrou-
tines are most efficient when M is a product of
small primes. M >= 0.
N (input) Number of columns to be transformed. These sub-
routines are most efficient when N is a product of
small primes. N >= 0.
A (input/output)
On entry, a two-dimensional array A(M,N) that con-
tains the sequences to be transformed.
LDA (input)
Leading dimension of the array containing the data
to be transformed. LDA >= M.
WORK (input)
On entry, an array with dimension of at least
LWORK. WORK must have been initialized by ZFFT2I.
LWORK (input)
The dimension of the array WORK. LWORK >= (4 * (M
+ N) + 30)