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NAME
     ssisl - solve the linear system  Ax  =  b  for  a  symmetric
     matrix A, which has been UDU-factored by xSICO or xSIFA, and
     vectors b and x.

SYNOPSIS
     SUBROUTINE DSISL (DA, LDA, N, IPIVOT, DB)

     SUBROUTINE SSISL (SA, LDA, N, IPIVOT, SB)

     SUBROUTINE ZSISL (ZA, LDA, N, IPIVOT, ZB)

     SUBROUTINE CSISL (CA, LDA, N, IPIVOT, CB)



     #include <sunperf.h>

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

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

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

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

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

ARGUMENTS
     xA        UDU factorization of the matrix A, as computed  by
               xSICO or xSIFA.

     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.

     IPIVOT    Pivot vector as computed by xSICO or xSIFA.

     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, IPIVOT(N), IROW
     C
           EXTERNAL          DSICO, DSISL
     C
     C     Initialize the array A to store the matrix A shown below.
     C     Initialize the array B to store the vector B shown below.
     C
     C         -.5   -.5   -.5   -.5        12
     C     A = -.5  -1.5  -1.5  -1.5    b =  6
     C         -.5  -1.5  -2.5  -2.5         6
     C         -.5  -1.5  -2.5  -3.5        12
     C
           DATA A / 4*-5.0D-1, -5.0D-1, 3*-1.5D0, -5.0D-1,
          $         -1.5D0, 2*-2.5D0, -5.0D-1, -1.5D0, -2.5D0, -3.5D0 /
           DATA B / 1.2D1, 6.0D0, 6.0D0, 1.2D1 /
     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 DSICO (A, LDA, N, IPIVOT, RCOND, WORK)
           IF ((RCOND + 1.0D0) .EQ. RCOND) THEN
             PRINT 1050
           END IF
           CALL DSISL (A, LDA, N, IPIVOT, B)
           PRINT 1060
           PRINT 1040, B
     C
      1000 FORMAT (1X, 'A in full form:')
      1010 FORMAT (4(3X, F5.1))
      1020 FORMAT (/1X, 'A in symmetric form:  (* in unused elements)')
      1030 FORMAT (/1X, 'b:')
      1040 FORMAT (3X, F5.1)
      1050 FORMAT (/1X, 'A may be singular to working precision.')
      1060 FORMAT (/1X, 'A**(-1) * b:')
     C
           END

SAMPLE OUTPUT
      A in full form:
         -0.5    -0.5    -0.5    -0.5
         -0.5    -1.5    -1.5    -1.5
         -0.5    -1.5    -2.5    -2.5
         -0.5    -1.5    -2.5    -3.5

      A in symmetric form:  (* in unused elements)
         -0.5    -0.5    -0.5    -0.5
         -0.5    -1.5    -1.5    -1.5
         -0.5    -1.5    -2.5    -2.5
         -0.5    -1.5    -2.5    -3.5

      b:
         12.0
          6.0
          6.0
         12.0

      A**(-1) * b:
        -30.0
          6.0
          6.0
         -6.0

Партнёры:

Хостинг: