DSPDI(3F)

NAME
     DSPDI   - DSPDI computes the determinant, inertia and inverse of a double
     precision symmetric matrix using the factors from DSPFA, where the matrix
     is stored in packed form.


SYNOPSYS
      SUBROUTINE DSPDI(AP,N,KPVT,DET,INERT,WORK,JOB)

DESCRIPTION
     On Entry

     AP DOUBLE PRECISION (N*(N+1)/2)
        the output from DSPFA.

     N INTEGER
        the order of the matrix A.

     KPVT INTEGER(N)
        the pivot vector from DSPFA.

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

     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.

     AP contains the upper triangle of the inverse of
        the original matrix, stored in packed form.
        The columns of the upper triangle are stored
        sequentially in a one-dimensional array.

     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 will occur if the inverse is requested and  DSPCO  has
     set RCOND .EQ. 0.0 or  DSPFA  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