zfftb - 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.
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);
Oracle Solaris Studio Performance Library zfftb(3P) NAME zfftb - 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. 7 Nov 2015 zfftb(3P)