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NAME
     dppsl - solve the linear system Ax = b for a symmetric posi-
     tive  definite  matrix  A  in packed storage, which has been
     Cholesky-factored by xPPCO or xPPFA, and vectors b and x.

SYNOPSIS
     SUBROUTINE DPPSL (DA, N, DB)

     SUBROUTINE SPPSL (SA, N, SB)

     SUBROUTINE ZPPSL (ZA, N, ZB)

     SUBROUTINE CPPSL (CA, N, CB)



     #include <sunperf.h>

     void dppsl(double *dap, int n, double *b) ;

     void sppsl(float *sap, int n, float *b) ;

     void cppsl(complex *cap, int n, complex *b) ;

     void zppsl(doublecomplex *zap, int n, doublecomplex *b) ;

ARGUMENTS
     xA        Cholesky factorization of the matrix  A,  as  com-
               puted by xPPCO or xPPFA.

     N         Order of the matrix A.  N >= 0.

     xB        On entry, the right-hand side vector b.  On  exit,
               the solution vector x.

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER           LENGTA, N
           PARAMETER        (N = 4)
           PARAMETER        (LENGTA = (N * N + N) / 2)
     C
           DOUBLE PRECISION  A(LENGTA), B(N), RCOND, WORK(N)
           INTEGER           INFO
     C
           EXTERNAL          DPPCO, DPPSL
     C
     C     Initialize the array A to store in packed symmetric storage
     C     mode the matrix A shown below.  Initialize the array B to store
     C     the matrix B shown below.
     C
     C         4  3  2  1        20
     C     A = 3  4  3  2    b = 20
     C         2  3  4  3        20
     C         1  2  3  4        20
     C
           DATA A / 4.0D0, 3.0D0, 4.0D0, 2.0D0, 3.0D0, 4.0D0,
          $         1.0D0, 2.0D0, 3.0D0, 4.0D0 /
           DATA B / 4*2.0D1 /
     C
           PRINT 1000
           PRINT 1010, A(1), A(2), A(4), A(7)
           PRINT 1010, A(2), A(3), A(5), A(8)
           PRINT 1010, A(4), A(5), A(6), A(9)
           PRINT 1010, A(7), A(8), A(9), A(10)
           PRINT 1020
           PRINT 1030, B
           CALL DPPCO (A, N, RCOND, WORK, INFO)
           IF ((RCOND + 1.0D0) .EQ. RCOND) THEN
             PRINT 1040
           END IF
           CALL DPPSL (A, N, B)
           PRINT 1050
           PRINT 1030, B
     C
      1000 FORMAT (1X, 'A in full form:')
      1010 FORMAT (5(3X, F7.3))
      1020 FORMAT (/1X, 'b:')
      1030 FORMAT (3X, F7.3)
      1040 FORMAT (1X, 'A may be singular to working precision.')
      1050 FORMAT (/1X, 'A**(-1) * b:')
     C
           END

SAMPLE OUTPUT
      A in full form:
          4.000     3.000     2.000     1.000
          3.000     4.000     3.000     2.000
          2.000     3.000     4.000     3.000
          1.000     2.000     3.000     4.000

      b:
         20.000
         20.000
         20.000
         20.000

      A**(-1) * b:
          4.000
          0.000
          0.000
          4.000

Партнёры:

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