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NAME
     spodi - compute the determinant and inverse of  a  symmetric
     positive definite matrix A, which has been Cholesky-factored
     by xPOCO, xPOFA, or xQRDC.

SYNOPSIS
     SUBROUTINE DPODI (DA, LDA, N, DDET, JOB)

     SUBROUTINE SPODI (SA, LDA, N, SDET, JOB)

     SUBROUTINE ZPODI (ZA, LDA, N, DDET, JOB)

     SUBROUTINE CPODI (CA, LDA, N, SDET, JOB)



     #include <sunperf.h>

     void dpodi(double *da, int lda,  int  n,  double  *det,  int
               job);

     void spodi(float *sa, int lda, int n, float *det, int job);

     void cpodi(complex *ca, int lda,  int  n,  float  *det,  int
               job);

     void zpodi(doublecomplex *za, int lda, int n,  double  *det,
               int job);

ARGUMENTS
     xA        On entry, the Cholesky factorization of the matrix
               A,  as  computed  by  xPOCO,  xPOFA, or xQRDC.  On
               exit, the inverse of the original matrix A if  the
               inverse  was  requested, otherwise A is unchanged.
               The strict lower triangle of A is not referenced.

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

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

     xDET      On exit, the determinant of  the  matrix  A.   The
               determinant is stored as b * (10 ** expon) where b
               is stored in DET(1) and expon is stored in DET(2).
               1.0 <= |DET(1)| <= 10.0  or  DET(1) = 0.0.

     JOB       Determines which  operation  the  subroutine  will
               perform:
                    11   both determinant and inverse
                    01   inverse only
                    10   determinant only

SAMPLE PROGRAM
           PROGRAM TEST
           IMPLICIT NONE
     C
           INTEGER           INVDET, LDA, N
           PARAMETER        (INVDET = 11)
           PARAMETER        (N = 4)
           PARAMETER        (LDA = N)
     C
           DOUBLE PRECISION  A(LDA,N), DET(2)
           INTEGER           ICOL, INFO, IROW, JOB
     C
           EXTERNAL          DPODI, DPOFA
     C
     C     Initialize the array A to store in symmetric storage mode
     C     the matrix A shown below.
     C
     C         4  3  2  1
     C     A = 3  4  3  2
     C         2  3  4  3
     C         1  2  3  4
     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 /
     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)
           CALL DPOFA (A, LDA, N, INFO)
           IF (INFO .EQ. 0) THEN
             JOB = INVDET
             CALL DPODI (A, LDA, N, DET, JOB)
             PRINT 1050
             DO 110, IROW = 1, N
               PRINT 1010, (A(ICOL,IROW), ICOL = 1, IROW),
          $                (A(IROW,ICOL), ICOL = IROW + 1, N)
       110   CONTINUE
             PRINT 1060, DET(1) * (10.0D0 ** DET(2))
           ELSE
             PRINT 1070
           END IF
     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**(-1):')
      1060 FORMAT (/1X, 'The determinant of A is ', F5.1)
      1070 FORMAT (/1X, 'A is not positive definite.')
     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

      A**(-1):
          0.600    -0.500     0.000     0.100
         -0.500     1.000    -0.500     0.000
          0.000    -0.500     1.000    -0.500
          0.100     0.000    -0.500     0.600

      The determinant of A is  20.0

Партнёры:

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