ZSYTRI - compute the inverse of a complex symmetric indef­
       inite 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 indefi­
       nite 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 mul­
               tipliers  used to obtain the factor U or L as com­
               puted 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 struc­
               ture of D as determined by ZSYTRF.

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

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


Man(1) output converted with man2html