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