redhat man page for dsytri

DSYTRI(l)								 )								 DSYTRI(l)

NAME
       DSYTRI  -  compute  the	inverse  of  a real symmetric indefinite matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by
       DSYTRF

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

	   CHARACTER	  UPLO

	   INTEGER	  INFO, LDA, N

	   INTEGER	  IPIV( * )

	   DOUBLE	  PRECISION A( LDA, * ), WORK( * )

PURPOSE
       DSYTRI computes the inverse of a real symmetric indefinite matrix A using the factorization A =	U*D*U**T  or  A  =  L*D*L**T  computed	by
       DSYTRF.

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) DOUBLE PRECISION 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 DSYTRF.

	       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 DSYTRF.

       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 version 3.0						   15 June 2000 							 DSYTRI(l)