sfftc - pute the forward Fast Fourier Transform of a real sequence.
SUBROUTINE SFFTC(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER IOPT, N, IFAC(*), LWORK, IERR COMPLEX Y(*) REAL X(*), SCALE, TRIGS(*), WORK(*) SUBROUTINE SFFTC_64(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER*8 IOPT, N, IFAC(*), LWORK, IERR REAL X(*), SCALE, TRIGS(*), WORK(*) COMPLEX Y(*) F95 INTERFACE SUBROUTINE FFT(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER*4, INTENT(IN) :: IOPT INTEGER*4, INTENT(IN), OPTIONAL :: N, LWORK REAL, INTENT(IN), OPTIONAL :: SCALE REAL, INTENT(IN), DIMENSION(:) :: X COMPLEX, INTENT(OUT), DIMENSION(:) :: Y REAL, INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER*4, INTENT(INOUT), DIMENSION(:) :: IFAC REAL, INTENT(OUT), DIMENSION(:) :: WORK INTEGER*4, INTENT(OUT) :: IERR SUBROUTINE FFT_64(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER(8), INTENT(IN) :: IOPT INTEGER(8), INTENT(IN), OPTIONAL :: N, LWORK REAL, INTENT(IN), OPTIONAL :: SCALE REAL, INTENT(IN), DIMENSION(:) :: X COMPLEX, INTENT(OUT), DIMENSION(:) :: Y REAL, INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER(8), INTENT(INOUT), DIMENSION(:) :: IFAC REAL, INTENT(OUT), DIMENSION(:) :: WORK INTEGER(8), INTENT(OUT) :: IERR C INTERFACE #include <sunperf.h> void sfftc_ (int *iopt, int *n, float *scale, float *x, complex *y, float *trigs, int *ifac, float *work, int *lwork, int *ierr); void sfftc_64_ (long *iopt, long *n, float *scale, float *x, complex *y, float *trigs, long *ifac, float *work, long *lwork, long *ierr);
Oracle Solaris Studio Performance Library sfftc(3P) NAME sfftc - initialize the trigonometric weight and factor tables or com- pute the forward Fast Fourier Transform of a real sequence. SYNOPSIS SUBROUTINE SFFTC(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER IOPT, N, IFAC(*), LWORK, IERR COMPLEX Y(*) REAL X(*), SCALE, TRIGS(*), WORK(*) SUBROUTINE SFFTC_64(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER*8 IOPT, N, IFAC(*), LWORK, IERR REAL X(*), SCALE, TRIGS(*), WORK(*) COMPLEX Y(*) F95 INTERFACE SUBROUTINE FFT(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER*4, INTENT(IN) :: IOPT INTEGER*4, INTENT(IN), OPTIONAL :: N, LWORK REAL, INTENT(IN), OPTIONAL :: SCALE REAL, INTENT(IN), DIMENSION(:) :: X COMPLEX, INTENT(OUT), DIMENSION(:) :: Y REAL, INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER*4, INTENT(INOUT), DIMENSION(:) :: IFAC REAL, INTENT(OUT), DIMENSION(:) :: WORK INTEGER*4, INTENT(OUT) :: IERR SUBROUTINE FFT_64(IOPT, N, SCALE, X, Y, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER(8), INTENT(IN) :: IOPT INTEGER(8), INTENT(IN), OPTIONAL :: N, LWORK REAL, INTENT(IN), OPTIONAL :: SCALE REAL, INTENT(IN), DIMENSION(:) :: X COMPLEX, INTENT(OUT), DIMENSION(:) :: Y REAL, INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER(8), INTENT(INOUT), DIMENSION(:) :: IFAC REAL, INTENT(OUT), DIMENSION(:) :: WORK INTEGER(8), INTENT(OUT) :: IERR C INTERFACE #include <sunperf.h> void sfftc_ (int *iopt, int *n, float *scale, float *x, complex *y, float *trigs, int *ifac, float *work, int *lwork, int *ierr); void sfftc_64_ (long *iopt, long *n, float *scale, float *x, complex *y, float *trigs, long *ifac, float *work, long *lwork, long *ierr); PURPOSE sfftc initializes the trigonometric weight and factor tables or com- putes the forward Fast Fourier Transform of a real sequence as follows: N-1 Y(k) = scale * SUM W*X(j) j=0 where k ranges from 0 to N-1 i = sqrt(-1) isign = -1 for forward transform W = exp(isign*i*j*k*2*pi/N) In real-to-complex transform of length N, the (N/2+1) complex output data points stored are the positive-frequency half of the spectrum of the Discrete Fourier Transform. The other half can be obtained through complex conjugation and therefore is not stored. ARGUMENTS IOPT (input) Integer specifying the operation to be performed: IOPT = 0 computes the trigonometric weight table and factor table IOPT = -1 computes forward FFT N (input) Integer specifying length of the input sequence X. N is most efficient when it is a product of small primes. N >= 0. Unchanged on exit. SCALE (input) Real scalar by which transform results are scaled. Unchanged on exit. X (input) On entry, X is a real array whose first N elements contain the sequence to be transformed. Y (output) Complex array whose first (N/2+1) elements contain the trans- form results. X and Y may be the same array starting at the same memory location, in which case the dimension of X must be at least 2*(N/2+1). Otherwise, it is assumed that there is no overlap between X and Y in memory. TRIGS (input/output) Real array of length 2*N that contains the trigonometric weights. The weights are computed when the routine is called with IOPT = 0 and they are used in subsequent calls when IOPT = -1. Unchanged on exit. IFAC (input/output) Integer array of dimension at least 128 that contains the factors of N. The factors are computed when the routine is called with IOPT = 0 and they are used in subsequent calls where IOPT = -1. Unchanged on exit. WORK (workspace) Real array of dimension at least N. The user can also choose to have the routine allocate its own workspace (see LWORK). LWORK (input) Integer specifying workspace size. If LWORK = 0, the routine will allocate its own workspace. IERR (output) On exit, integer IERR has one of the following values: 0 = normal return -1 = IOPT is not 0 or -1 -2 = N < 0 -3 = (LWORK is not 0) and (LWORK is less than N) -4 = memory allocation for workspace failed SEE ALSO fft 7 Nov 2015 sfftc(3P)