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NAME
     dcosqi - initialize the array xWSAVE, which is used in  both
     xCOSQF and xCOSQB.

SYNOPSIS
     SUBROUTINE COSQI (N, RWSAVE)

     SUBROUTINE DCOSQI (N, DWSAVE)

     SUBROUTINE VCOSQI (N, RWSAVE)

     SUBROUTINE VDCOSQI (N, DWSAVE)



     #include <sunperf.h>

     void costi (int n, float *rwsave) ;

     void dcosti (int n, double *dwsave) ;

     void vcosti (int n, float *rwsave) ;

     void vdcosti (int n, float *dwsave) ;

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

     xWSAVE    On entry, an array with a dimension of at least (3
               *  N  + 15) for scalar subroutines or (2 * N + 15)
               for vector subroutines.  The same work  array  can
               be  used  for  both xCOSQF and xCOSQB as long as N
               remains unchanged.  Different  xWSAVE  arrays  are
               required for different values of N.  This initial-
               ization does not have to be repeated between calls
               to xCOSQF or xCOSQB as long as N and xWSAVE remain
               unchanged,  thus  subsequent  transforms  can   be
               obtained faster than the first.

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER       N
           PARAMETER    (N = 6)
     C
           INTEGER       I
           REAL          PI, WSAVE(3 * N + 15), X(N)
     C
           EXTERNAL      COSQB, COSQF, COSQI
           INTRINSIC     ACOS, COS
     C
     C     Initialize array X to a real even quarter-wave sequence, that is,
     C     it can be expanded in terms of a cosine series with only odd wave
     C     numbers.
     C
           PI = ACOS (-1.0)
           DO 100, I=1, N
             X(I) = COS((I - 1) * PI / (2.0 * N))
       100 CONTINUE
     C
           CALL COSQI (N, WSAVE)
           PRINT 1000
           PRINT 1010, (X(I), I = 1, N)
           CALL COSQF (N, X, WSAVE)
           PRINT 1020
           PRINT 1010, (X(I), I = 1, N)
           CALL COSQB (N, X, WSAVE)
           PRINT 1030
           PRINT 1010, (X(I), I = 1, N)
     C
      1000 FORMAT(1X, 'Original Sequence: ')
      1010 FORMAT(1X, 100(F7.3, 1X))
      1020 FORMAT(1X, 'Transformed Sequence: ')
      1030 FORMAT(1X, 'Recovered Sequence: ')
           END

SAMPLE OUTPUT
      Original Sequence:
        1.000   0.966   0.866   0.707   0.500   0.259
      Transformed Sequence:
        6.000   0.000   0.000   0.000   0.000   0.000
      Recovered Sequence:
       24.000  23.182  20.785  16.971  12.000   6.212

Партнёры:

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