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NAME
     vdcosqb - synthesize a Fourier sequence from its representa-
     tion in terms of a cosine series with odd wave numbers.  The
     xCOSQ operations are unnormalized inverses of themselves, so
     a  call to xCOSQF followed by a call to xCOSQB will multiply
     the input sequence by 4 * N.  The VxCOSQ operations are nor-
     malized,  so a call of VxCOSQF followed by a call of VxCOSQB
     will return the original sequence.

SYNOPSIS
     SUBROUTINE COSQB (N, RX, RWSAVE)

     SUBROUTINE DCOSQB (N, DX, DWSAVE)

     SUBROUTINE VCOSQB (M, N, RX, RXT, MDIMX, RWSAVE)

     SUBROUTINE VDCOSQB (M, N, DX, DXT, MDIMX, DWSAVE)



     #include <sunperf.h>

     void cosqb (int n, float *sx, float *wsave) ;

     void dcosqb (int n, double *dx, double *wsave) ;

     void vcosqb(int m,  int  n,  float  *sx,  int  mdimx,  float
               *wsave) ;

     void vdcosqb(int m, int n, double  *dx,  int  mdimx,  double
               *wsave) ;

ARGUMENTS
     M         (For vector operations only.)
               The number of sequences to be transformed.   M  >=
               0.

     N         Length of the sequence to be  transformed.   These
               subroutines are most efficient when N is a product
               of small primes.  N >= 0.

     xX        On entry, an array  of  length  N  containing  the
               sequence  to  be transformed.  For VxCOSQB, a real
               two-dimensional array with dimensions of (MDIMX  x
               N)   whose   rows  contain  the  sequences  to  be
               transformed.  On  exit,  the  quarter-wave  cosine
               synthesis of the input.

     xXT       (For vector operations only.)
               A real two-dimensional work array with  dimensions
               of (MDIMX x N).

     MDIMX     (For vector operations only.)
               Leading dimension of the  arrays  xX  and  xXT  as
               specified  in a dimension or type statement. MDIMX
               >= M.

     xWSAVE    On entry, an array with dimension of at least (3 *
               N + 15) for scalar subroutines or (2 * N + 15) for
               vector  subroutines,  initialized  by  xCOSQI   or
               VxCOSQI.

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER          M, N
           PARAMETER       (M = 1)
           PARAMETER       (N = 6)
     C
           INTEGER          I
           REAL             PI,  WSAVE(N + 15), X(M, N), XT(M, N)
     C
           EXTERNAL         VCOSQB, VCOSQF, VCOSQI
           INTRINSIC        ACOS, COS
     C
     C     Initialize the first row of the  array to a real even
     C     quarter-wave sequence, that is, it can be expanded in
     C     terms of a cosine series with only only odd wave numbers.
     C
           PI = ACOS (-1.0)
           DO 100, I=1, N
             X(M,I) = 40.0 * COS ((I - 1) * PI / (2.0 * N))
       100 CONTINUE
     C
           PRINT 1000
           PRINT 1010, (X(M, I), I = 1, N)
           CALL VCOSQI (N, WSAVE)
           CALL VCOSQF (M, N, X, XT, M, WSAVE)
           PRINT 1020
           PRINT 1010, (X(M, I), I = 1, N)
           CALL VCOSQB (M, N, X, XT, M, WSAVE)
           PRINT 1030
           PRINT 1010, (X(M, I), I = 1, N)
     C
      1000 FORMAT (1X, 'Original Sequence: ')
      1010 FORMAT (1X, 100(F5.1, 1X))
      1020 FORMAT (1X, 'Transformed Sequence: ')
      1030 FORMAT (1X, 'Recovered Sequence: ')
     C
           END

SAMPLE OUTPUT
      Original Sequence:
       40.0  38.6  34.6  28.3  20.0  10.4
      Transformed Sequence:
       49.0   0.0   0.0   0.0   0.0   0.0
      Recovered Sequence:
       40.0  38.6  34.6  28.3  20.0  10.4

Партнёры:

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