dfftz2 - pute the two-dimensional forward Fast Fourier Transform of a two-dimen- sional double precision array.
SUBROUTINE DFFTZ2(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER IOPT, M, N, LDX, LDY, IFAC(*), LWORK, IERR DOUBLE COMPLEX Y(LDY, *) DOUBLE PRECISION X(LDX, *), SCALE, TRIGS(*), WORK(*) SUBROUTINE DFFTZ2_64(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER*8 IOPT, M, N, LDX, LDY, IFAC(*), LWORK, IERR DOUBLE COMPLEX Y(LDY, *) DOUBLE PRECISION X(LDX, *), SCALE, TRIGS(*), WORK(*) F95 INTERFACE SUBROUTINE FFT2(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER, INTENT(IN) :: IOPT INTEGER, INTENT(IN), OPTIONAL :: M, N, LDX, LDY, LWORK REAL(8), INTENT(IN), OPTIONAL :: SCALE REAL(8), INTENT(IN), DIMENSION(:,:) :: X COMPLEX(8), INTENT(OUT), DIMENSION(:,:) :: Y REAL(8), INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER, INTENT(INOUT), DIMENSION(:) :: IFAC REAL(8), INTENT(OUT), DIMENSION(:) :: WORK INTEGER, INTENT(OUT) :: IERR SUBROUTINE FFT2_64(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER(8), INTENT(IN) :: IOPT INTEGER(8), INTENT(IN), OPTIONAL :: M, N, LDX, LDY, LWORK REAL(8), INTENT(IN), OPTIONAL :: SCALE REAL(8), INTENT(IN), DIMENSION(:,:) :: X COMPLEX(8), INTENT(OUT), DIMENSION(:,:) :: Y REAL(8), INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER(8), INTENT(INOUT), DIMENSION(:) :: IFAC REAL(8), INTENT(OUT), DIMENSION(:) :: WORK INTEGER(8), INTENT(OUT) :: IERR C INTERFACE #include <sunperf.h> void dfftz2_ (int *iopt, int *n1, int *n2, double *scale, double *x, int *ldx, doublecomplex *y, int *ldy, double *trigs, int *ifac, double *work, int *lwork, int *ierr); void dfftz2_64_ (long *iopt, long *n1, long *n2, double *scale, double *x, long *ldx, doublecomplex *y, long *ldy, double *trigs, long *ifac, double *work, long *lwork, long *ierr);
Oracle Solaris Studio Performance Library dfftz2(3P) NAME dfftz2 - initialize the trigonometric weight and factor tables or com- pute the two-dimensional forward Fast Fourier Transform of a two-dimen- sional double precision array. SYNOPSIS SUBROUTINE DFFTZ2(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER IOPT, M, N, LDX, LDY, IFAC(*), LWORK, IERR DOUBLE COMPLEX Y(LDY, *) DOUBLE PRECISION X(LDX, *), SCALE, TRIGS(*), WORK(*) SUBROUTINE DFFTZ2_64(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER*8 IOPT, M, N, LDX, LDY, IFAC(*), LWORK, IERR DOUBLE COMPLEX Y(LDY, *) DOUBLE PRECISION X(LDX, *), SCALE, TRIGS(*), WORK(*) F95 INTERFACE SUBROUTINE FFT2(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER, INTENT(IN) :: IOPT INTEGER, INTENT(IN), OPTIONAL :: M, N, LDX, LDY, LWORK REAL(8), INTENT(IN), OPTIONAL :: SCALE REAL(8), INTENT(IN), DIMENSION(:,:) :: X COMPLEX(8), INTENT(OUT), DIMENSION(:,:) :: Y REAL(8), INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER, INTENT(INOUT), DIMENSION(:) :: IFAC REAL(8), INTENT(OUT), DIMENSION(:) :: WORK INTEGER, INTENT(OUT) :: IERR SUBROUTINE FFT2_64(IOPT, M, N, SCALE, X, LDX, Y, LDY, TRIGS, IFAC, WORK, LWORK, IERR) INTEGER(8), INTENT(IN) :: IOPT INTEGER(8), INTENT(IN), OPTIONAL :: M, N, LDX, LDY, LWORK REAL(8), INTENT(IN), OPTIONAL :: SCALE REAL(8), INTENT(IN), DIMENSION(:,:) :: X COMPLEX(8), INTENT(OUT), DIMENSION(:,:) :: Y REAL(8), INTENT(INOUT), DIMENSION(:) :: TRIGS INTEGER(8), INTENT(INOUT), DIMENSION(:) :: IFAC REAL(8), INTENT(OUT), DIMENSION(:) :: WORK INTEGER(8), INTENT(OUT) :: IERR C INTERFACE #include <sunperf.h> void dfftz2_ (int *iopt, int *n1, int *n2, double *scale, double *x, int *ldx, doublecomplex *y, int *ldy, double *trigs, int *ifac, double *work, int *lwork, int *ierr); void dfftz2_64_ (long *iopt, long *n1, long *n2, double *scale, double *x, long *ldx, doublecomplex *y, long *ldy, double *trigs, long *ifac, double *work, long *lwork, long *ierr); PURPOSE dfftz2 initializes the trigonometric weight and factor tables or com- putes the two-dimensional forward Fast Fourier Transform of a two-dimensional double precision array. In computing the two-dimen- sional FFT, one-dimensional FFTs are computed along the columns of the input array. One-dimensional FFTs are then computed along the rows of the intermediate results. N-1 M-1 Y(k1,k2) = scale * SUM SUM W2*W1*X(j1,j2) j2=0 j1=0 where k1 ranges from 0 to M-1 and k2 ranges from 0 to N-1 i = sqrt(-1) isign = -1 for forward transform W1 = exp(isign*i*j1*k1*2*pi/M) W2 = exp(isign*i*j2*k2*2*pi/N) In real-to-complex transform of length M, the (M/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 M (input) Integer specifying length of the transform in the first dimension. M is most efficient when it is a product of small primes. M >= 0. Unchanged on exit. N (input) Integer specifying length of the transform in the second dimension. N is most efficient when it is a product of small primes N >= 0. Unchanged on exit. SCALE (input) Double precision scalar by which transform results are scaled. Unchanged on exit. X (input) X is a double precision array of dimensions (LDX, N) that contains input data to be transformed. X and Y can be the same array. LDX (input) Leading dimension of X. LDX >= M if X is not the same array as Y. Else, LDX = 2*LDY. Unchanged on exit. Y (output) Y is a double complex array of dimensions (LDY, N) that con- tains the transform results. X and Y can be the same array starting at the same memory location, in which case the input data are overwritten by their transform results. Otherwise, it is assumed that there is no overlap between X and Y in memory. LDY (input) Leading dimension of Y. LDY >= M/2+1 Unchanged on exit. TRIGS (input/output) Double precision array of length 2*(M+N) that contains the trigonometric weights. The weights are computed when the routine is called with IOPT = 0 and they are used in subse- quent calls when IOPT = -1. Unchanged on exit. IFAC (input/output) Integer array of dimension at least 2*128 that contains the factors of M and N. The factors are computed when the rou- tine is called with IOPT = 0 and they are used in subsequent calls when IOPT = -1. Unchanged on exit. WORK (workspace) Double precision array of dimension at least MAX(M, 2*N) where NCPUS is the number of threads used to execute the rou- tine. 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 = M < 0 -3 = N < 0 -4 = (LDX < M) or (LDX not equal 2*LDY when X and Y are same array) -5 = (LDY < M/2+1) -6 = (LWORK not equal 0) and (LWORK < MAX(M,2*N)) -7 = memory allocation failed SEE ALSO fft CAUTIONS On exit, output array Y(1:LDY, 1:N) is overwritten. 7 Nov 2015 dfftz2(3P)