Contents
vdfftf - compute the Fourier coefficients of a periodic
sequence. The VRFFT operations are normalized, so a call of
VRFFTF followed by a call of VRFFTB will return the original
sequence.
SUBROUTINE VDFFTF(M, N, X, XT, MDIMX, WSAVE)
INTEGER M, N, MDIMX
DOUBLE PRECISION X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
SUBROUTINE VDFFTF_64(M, N, X, XT, MDIMX, WSAVE)
INTEGER*8 M, N, MDIMX
DOUBLE PRECISION X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
F95 INTERFACE
SUBROUTINE FFTF([M], [N], X, XT, [MDIMX], WSAVE)
INTEGER :: M, N, MDIMX
REAL(8), DIMENSION(:) :: WSAVE
REAL(8), DIMENSION(:,:) :: X, XT
SUBROUTINE FFTF_64([M], [N], X, XT, [MDIMX], WSAVE)
INTEGER(8) :: M, N, MDIMX
REAL(8), DIMENSION(:) :: WSAVE
REAL(8), DIMENSION(:,:) :: X, XT
C INTERFACE
#include <sunperf.h>
void vdfftf(int m, int n, double *x, double *xt, int mdimx,
double *wsave);
void vdfftf_64(long m, long n, double *x, double *xt, long
mdimx, double *wsave);
M (input)
The number of sequences to be transformed. M >=
0.
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. For VRFFTF, a real
two- dimensional array X(M,N) whose rows contain
the sequences to be transformed.
XT (input)
A real two-dimensional work array with dimensions
of (MDIMX x N).
MDIMX (input)
Leading dimension of the arrays X and XT as speci-
fied in a dimension or type statement. MDIMX >=
M.
WSAVE (input)
On entry, an array of dimension (N+15) or greater
initialized by VRFFTI.