zsytri(3F)

NAME
     ZSYTRI - compute the inverse of a complex symmetric indefinite matrix A
     using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF

SYNOPSIS
     SUBROUTINE ZSYTRI( UPLO, N, A, LDA, IPIV, WORK, INFO )

         CHARACTER      UPLO

         INTEGER        INFO, LDA, N

         INTEGER        IPIV( * )

         COMPLEX*16     A( LDA, * ), WORK( * )

PURPOSE
     ZSYTRI computes the inverse of a complex symmetric indefinite matrix A
     using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF.


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.

     A       (input/output) COMPLEX*16 array, dimension (LDA,N)
             On entry, the block diagonal matrix D and the multipliers used to
             obtain the factor U or L as computed by ZSYTRF.

             On exit, if INFO = 0, the (symmetric) inverse of the original
             matrix.  If UPLO = 'U', the upper triangular part of the inverse
             is formed and the part of A below the diagonal is not referenced;
             if UPLO = 'L' the lower triangular part of the inverse is formed
             and the part of A above the diagonal is not referenced.

     LDA     (input) INTEGER
             The leading dimension of the array A.  LDA >= max(1,N).

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

     WORK    (workspace) COMPLEX*16 array, dimension (2*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.