• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• ARGUMENTS

NAME

vzfftf - compute the Fourier coefficients of a periodic sequence. The VZFFT operations are normalized, so a call of VZFFTF followed by a call of VZFFTB will return the original sequence.

SYNOPSIS

  SUBROUTINE VZFFTF( M, N, X, XT, MDIMX, ROWCOL, WSAVE)
  CHARACTER * 1 ROWCOL
  DOUBLE COMPLEX X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
  INTEGER M, N, MDIMX

  SUBROUTINE VZFFTF_64( M, N, X, XT, MDIMX, ROWCOL, WSAVE)
  CHARACTER * 1 ROWCOL
  DOUBLE COMPLEX X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
  INTEGER*8 M, N, MDIMX

F95 INTERFACE

  SUBROUTINE FFTF( [M], [N], X, XT, [MDIMX], ROWCOL, WSAVE)
  CHARACTER(LEN=1) :: ROWCOL
  COMPLEX(8), DIMENSION(:) :: WSAVE
  COMPLEX(8), DIMENSION(:,:) :: X, XT
  INTEGER :: M, N, MDIMX

  SUBROUTINE FFTF_64( [M], [N], X, XT, [MDIMX], ROWCOL, WSAVE)
  CHARACTER(LEN=1) :: ROWCOL
  COMPLEX(8), DIMENSION(:) :: WSAVE
  COMPLEX(8), DIMENSION(:,:) :: X, XT
  INTEGER(8) :: M, N, MDIMX

C INTERFACE

#include <sunperf.h>

void vzfftf(int m, int n, doublecomplex *x, doublecomplex *xt, int mdimx, char rowcol, doublecomplex *wsave);

void vzfftf_64(long m, long n, doublecomplex *x, doublecomplex *xt, long mdimx, char rowcol, doublecomplex *wsave);

ARGUMENTS

• 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/output)
  On entry, an array X(M,N) whose rows contain the sequences to be transformed.

• XT (input)
  A work array.

• MDIMX (input)
  Leading dimension of the arrays X and XT as specified in a dimension or type statement. MDIMX > = M.

• ROWCOL (input)
  Indicates whether to transform rows ('R' or 'r') or columns ('C' or 'c').

• WSAVE (input)
  On entry, an array of dimension (K+15) or greater, where K = M if ROWCOL = ('R' or 'r'). Otherwise, K = N. WSAVE is initialized by VZFFTI.