DSIDI(3F)

NAME
     DSIDI   - DSIDI computes the determinant, inertia and inverse of a double
     precision symmetric matrix using the factors from DSIFA.


SYNOPSYS
      SUBROUTINE DSIDI(A,LDA,N,KPVT,DET,INERT,WORK,JOB)

DESCRIPTION
     On Entry

     A DOUBLE PRECISION(LDA,N)
        the output from DSIFA.

     LDA INTEGER
        the leading dimension of the array A.

     N INTEGER
        the order of the matrix A.

     KPVT INTEGER(N)
        the pivot vector from DSIFA.

     WORK DOUBLE PRECISION(N)
        work vector.  Contents destroyed.

     JOB INTEGER
        JOB has the decimal expansion  ABC  where
        if  C .NE. 0, the inverse is computed,
        if  B .NE. 0, the determinant is computed,
        if  A .NE. 0, the inertia is computed.
        For example, JOB = 111  gives all three.  On Return Variables not
     requested by JOB are not used.

     A contains the upper triangle of the inverse of
        the original matrix.  The strict lower triangle
        is never referenced.

     DET DOUBLE PRECISION(2)
        determinant of original matrix.
        DETERMINANT = DET(1) * 10.0**DET(2)
        with 1.0 .LE. DABS(DET(1)) .LT. 10.0
        or DET(1) = 0.0.

     INERT INTEGER(3)
        the inertia of the original matrix.
        INERT(1)  =  number of positive eigenvalues.
        INERT(2)  =  number of negative eigenvalues.
        INERT(3)  =  number of zero eigenvalues.  Error Condition

     A division by zero may occur if the inverse is requested and  DSICO  has
     set RCOND .EQ. 0.0 or  DSIFA  has set  INFO .NE. 0 .  LINPACK.  This
     version dated 08/14/78 .  James Bunch, Univ. Calif. San Diego, Argonne
     Nat. Lab Subroutines and Functions BLAS DAXPY,DCOPY,DDOT,DSWAP Fortran
     DABS,IABS,MOD