Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3  - computes the inverse of a real symmetric indefinite matrix A in packed storage
       using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF

SYNOPSIS

       SUBROUTINE DSPTRI( UPLO, N, AP, IPIV, WORK, INFO )

           CHARACTER      UPLO

           INTEGER        INFO, N

           INTEGER        IPIV( * )

           DOUBLE         PRECISION AP( * ), WORK( * )

PURPOSE

       DSPTRI computes the inverse of a real symmetric indefinite  matrix  A  in  packed  storage
       using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF.

ARGUMENTS

        UPLO    (input) CHARACTER*1
                Specifies whether the details of the factorization are stored
                as an upper or lower triangular matrix.
                = 'U':  Upper triangular, form is A = U*D*U**T;
                = 'L':  Lower triangular, form is A = L*D*L**T.

        N       (input) INTEGER
                The order of the matrix A.  N >= 0.

        AP      (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)
                On entry, the block diagonal matrix D and the multipliers
                used to obtain the factor U or L as computed by DSPTRF,
                stored as a packed triangular matrix.
                On exit, if INFO = 0, the (symmetric) inverse of the original
                matrix, stored as a packed triangular matrix. The j-th column
                of inv(A) is stored in the array AP as follows:
                if UPLO = 'U', AP(i + (j-1)*j/2) = inv(A)(i,j) for 1<=i<=j;
                if UPLO = 'L',
                AP(i + (j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.

        IPIV    (input) INTEGER array, dimension (N)
                Details of the interchanges and the block structure of D
                as determined by DSPTRF.

        WORK    (workspace) DOUBLE PRECISION array, dimension (N)

        INFO    (output) INTEGER
                = 0: successful exit
                < 0: if INFO = -i, the i-th argument had an illegal value
                > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
                inverse could not be computed.

 LAPACK routine (version 3.3.1)             April 2011                            DSPTRI(3lapack)