zfftb(3P) Sun Performance Library zfftb(3P)NAMEzfftb - compute a periodic sequence from its Fourier coefficients. The
FFT operations are unnormalized, so a call of ZFFTF followed by a call
of ZFFTB will multiply the input sequence by N.
SYNOPSIS
SUBROUTINE ZFFTB(N, X, WSAVE)
DOUBLE COMPLEX X(*)
INTEGER N
DOUBLE PRECISION WSAVE(*)
SUBROUTINE ZFFTB_64(N, X, WSAVE)
DOUBLE COMPLEX X(*)
INTEGER*8 N
DOUBLE PRECISION WSAVE(*)
F95 INTERFACE
SUBROUTINE FFTB([N], X, WSAVE)
COMPLEX(8), DIMENSION(:) :: X
INTEGER :: N
REAL(8), DIMENSION(:) :: WSAVE
SUBROUTINE FFTB_64([N], X, WSAVE)
COMPLEX(8), DIMENSION(:) :: X
INTEGER(8) :: N
REAL(8), DIMENSION(:) :: WSAVE
C INTERFACE
#include <sunperf.h>
void zfftb(int n, doublecomplex *x, double *wsave);
void zfftb_64(long n, doublecomplex *x, double *wsave);
ARGUMENTS
N (input) Length of the sequence to be transformed. These subroutines
are most efficient when N is a product of small primes. N >=
0.
X (input/output)
On entry, an array of length N containing the sequence to be
transformed.
WSAVE (input/output)
On entry, WSAVE must be an array of dimension (4 * N + 15) or
greater and must have been initialized by ZFFTI.
6 Mar 2009 zfftb(3P)