dfftf(3P) Sun Performance Library dfftf(3P)NAMEdfftf - compute the Fourier coefficients of a periodic sequence. The
FFT operations are unnormalized, so a call of DFFTF followed by a call
of DFFTB will multiply the input sequence by N.
SYNOPSIS
SUBROUTINE DFFTF(N, X, WSAVE)
INTEGER N
DOUBLE PRECISION X(*), WSAVE(*)
SUBROUTINE DFFTF_64(N, X, WSAVE)
INTEGER*8 N
DOUBLE PRECISION X(*), WSAVE(*)
F95 INTERFACE
SUBROUTINE FFTF([N], X, WSAVE)
INTEGER :: N
REAL(8), DIMENSION(:) :: X, WSAVE
SUBROUTINE FFTF_64([N], X, WSAVE)
INTEGER(8) :: N
REAL(8), DIMENSION(:) :: X, WSAVE
C INTERFACE
#include <sunperf.h>
void dfftf(int n, double *x, double *wsave);
void dfftf_64(long n, double *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 (2 * N + 15) or
greater and must have been initialized by DFFTI.
6 Mar 2009 dfftf(3P)