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NAME
     ezfftf - computes the Fourier  coefficients  of  a  periodic
     sequence.   EZFFTF  is  a  simplified  but slower version of
     RFFTF.

SYNOPSIS
     SUBROUTINE EZFFTF (N, R, AZERO, A, B, WSAVE)



     #include <sunperf.h>

     void ezfftf (int n, float *r, float *azero, float *a,  float
               *sb, float *wsave) ;

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

     R         A real array of length N containing  the  sequence
               to be transformed.  On exit, R is unchanged.

     AZERO     The sum from i=1 to i=n of r(i)/n

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

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER          N
           PARAMETER       (N = 9)
     C
           INTEGER          I
           REAL             A(N), B(N), AZERO, PI, R(N), WSAVE(3 * N + 15)
     C
           EXTERNAL         EZFFTB, EZFFTF, EZFFTI
           INTRINSIC        ACOS, COS, SIN
     C
     C     Initialize array to a sequence of real numbers.
     C
           PI = ACOS (-1.0)
           DO 100, I=1, N
             R(I) = 3.0 + SIN ((I - 1.0) * 2.0 * PI / N)  +
          $         4.0 * COS ((I - 1.0) * 8.0 * PI / N)
       100 CONTINUE
     C
           CALL EZFFTI (N, WSAVE)
           PRINT 1000
           PRINT 1010, (R(I), I = 1, N)
           CALL EZFFTF (N, R, AZERO, A, B, WSAVE)
           PRINT 1020, AZERO
           PRINT 1030
           PRINT 1010, (A(I), I = 1, N)
           PRINT 1040
           PRINT 1010, (B(I), I = 1, N)
           CALL EZFFTB (N, R, AZERO, A, B, WSAVE)
           PRINT 1050
           PRINT 1010, (R(I), I = 1, N)
     C
      1000 FORMAT (1X, 'Original Sequence: ')
      1010 FORMAT (100(F4.1, 1X))
      1020 FORMAT (1X, 'Azero = ' F4.1)
      1030 FORMAT (1X, 'A =  ')
      1040 FORMAT (1X, 'B = ')
      1050 FORMAT (1X, 'Recovered Sequence: ')
     C
           END

SAMPLE OUTPUT
      Original Sequence:
      7.0 -0.1  7.0  1.9  4.0  3.4  0.1  5.1 -1.4
      Azero =  3.0
      A =
      0.0  0.0  0.0  4.0  0.0  0.0  0.0  0.0  0.0
      B =
      1.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0
      Recovered Sequence:
      7.0 -0.1  7.0  1.9  4.0  3.4  0.1  5.1 -1.4

Партнёры:

Хостинг: