Contents

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

NAME

     dezftf - computes the Fourier  coefficients  of  a  periodic
     sequence.   DEZFTF  is  a  simplified  but slower version of
     DFFTF.

SYNOPSIS

     SUBROUTINE DEZFTF(N, R, AZERO, A, B, WSAVE)

     INTEGER N
     DOUBLE PRECISION AZERO
     DOUBLE PRECISION R(*), A(*), B(*), WSAVE(*)

     SUBROUTINE DEZFTF_64(N, R, AZERO, A, B, WSAVE)

     INTEGER*8 N
     DOUBLE PRECISION AZERO
     DOUBLE PRECISION R(*), A(*), B(*), WSAVE(*)

  F95 INTERFACE
     SUBROUTINE DEZFTF(N, R, AZERO, A, B, WSAVE)

     INTEGER :: N
     REAL(8) :: AZERO
     REAL(8), DIMENSION(:) :: R, A, B, WSAVE

     SUBROUTINE DEZFTF_64(N, R, AZERO, A, B, WSAVE)

     INTEGER(8) :: N
     REAL(8) :: AZERO
     REAL(8), DIMENSION(:) :: R, A, B, WSAVE

  C INTERFACE
     #include <sunperf.h>

     void dezftf(int n, double *r, double azero, double *a,  dou-
               ble *b, double *wsave);

     void dezftf_64(long n, double *r, double azero,  double  *a,
               double *b, double *wsave);

ARGUMENTS

     N (input) Length of the sequence  to  be  transformed.   The
               method  is most efficient when N is the product of
               small primes.  N >= 0.

     R (input) On entry, a real array of length N containing  the
               sequence   to  be  transformed.   On  exit,  R  is
               unchanged.

     AZERO (output)
               On exit, the sum from i=1 to i=n of r(i)/n.

     A (input/output)
               On  entry,  array  that  contains  the   remaining
               Fourier  coefficients.   On exit, these arrays are
               unchanged.

     B (input/output)
               On  entry,  array  that  contains  the   remaining
               Fourier  coefficients.   On exit, these arrays are
               unchanged.

     WSAVE (input)
               On entry, an array with dimension of at least (3 *
               N + 15), initialized by DEZFTI.