dezftf

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, double *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/output): 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.