cfftb
cfftb - compute a periodic sequence from its Fourier coefficients. The FFT operations are unnormalized, so a call of CFFTF followed by a call of CFFTB will multiply the input sequence by N.
SUBROUTINE CFFTB( N, X, WSAVE)
COMPLEX X(*)
INTEGER N
REAL WSAVE(*)
SUBROUTINE CFFTB_64( N, X, WSAVE)
COMPLEX X(*)
INTEGER*8 N
REAL WSAVE(*)
SUBROUTINE FFTB( [N], X, WSAVE)
COMPLEX, DIMENSION(:) :: X
INTEGER :: N
REAL, DIMENSION(:) :: WSAVE
SUBROUTINE FFTB_64( [N], X, WSAVE)
COMPLEX, DIMENSION(:) :: X
INTEGER(8) :: N
REAL, DIMENSION(:) :: WSAVE
#include <sunperf.h>
void cfftb(int n, complex *x, float *wsave);
void cfftb_64(long n, complex *x, float *wsave);
-
* 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)
-
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 CFFTI.