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NAME
     dposl - solve the linear system Ax = b for a symmetric posi-
     tive  definite matrix A, which has been Cholesky-factored by
     xPOCO or xPOFA, and vectors b and x.

SYNOPSIS
     SUBROUTINE DPOSL (DA, LDA, N, DB)

     SUBROUTINE SPOSL (SA, LDA, N, SB)

     SUBROUTINE ZPOSL (ZA, LDA, N, ZB)

     SUBROUTINE CPOSL (CA, LDA, N, CB)



     #include <sunperf.h>

     void dposl(double *da, int lda, int n, double *b) ;

     void sposl(float *sa, int lda, int n, float *b) ;

     void cposl(complex *ca, int lda, int n, complex *b) ;

     void zposl(doublecomplex *za, int lda, int n,  doublecomplex
               *b) ;

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

     LDA       Leading dimension of the array A as specified in a
               dimension or type statement.  LDA >= max(1,N).

     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           LDA, N
           PARAMETER        (N = 4)
           PARAMETER        (LDA = N)
     C
           DOUBLE PRECISION  A(LDA,N), B(N), RCOND, WORK(N)
           INTEGER           ICOL, INFO, IROW
     C
           EXTERNAL          DPOCO, DPOSL
     C
     C     Initialize the array A to store in symmetric storage mode
     C     the matrix A shown below.  Initialize the array B to store
     C     the vector 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*8D8, 3.0D0, 4.0D0, 2*8D8, 2.0D0, 3.0D0, 4.0D0,
          $         8D8, 1.0D0, 2.0D0, 3.0D0, 4.0D0 /
           DATA B / 4*2.0D1 /
     C
           PRINT 1000
           DO 100, IROW = 1, N
             PRINT 1010, (A(ICOL,IROW), ICOL = 1, IROW),
          $              (A(IROW,ICOL), ICOL = IROW + 1, N)
       100 CONTINUE
           PRINT 1020
           PRINT 1010, ((A(IROW,ICOL), ICOL = 1, N), IROW = 1, N)
           PRINT 1030
           PRINT 1040, B
           CALL DPOCO (A, LDA, N, RCOND, WORK, INFO)
           IF ((RCOND + 1.0D0) .EQ. 1.0D0) THEN
             PRINT 1050
           END IF
           CALL DPOSL (A, LDA, N, B)
           PRINT 1060
           PRINT 1040, B
     C
      1000 FORMAT (1X, 'A in full form:')
      1010 FORMAT (4(3X, F7.3))
      1020 FORMAT (/1X, 'A in symmetric form:  (* in unused entries)')
      1030 FORMAT (/1X, 'b:')
      1040 FORMAT (3X, F7.3)
      1050 FORMAT (/1X, 'A may be singular to working precision.')
      1060 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

      A in symmetric form:  (* in unused entries)
          4.000     3.000     2.000     1.000
        *******     4.000     3.000     2.000
        *******   *******     4.000     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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