CHETRI(l) ) CHETRI(l)
CHETRI - compute the inverse of a complex Hermitian indefinite matrix A using the factor-
ization A = U*D*U**H or A = L*D*L**H computed by CHETRF
SUBROUTINE CHETRI( UPLO, N, A, LDA, IPIV, WORK, INFO )
INTEGER INFO, LDA, N
INTEGER IPIV( * )
COMPLEX A( LDA, * ), WORK( * )
CHETRI computes the inverse of a complex Hermitian indefinite matrix A using the factor-
ization A = U*D*U**H or A = L*D*L**H computed by CHETRF.
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**H;
= 'L': Lower triangular, form is A = L*D*L**H.
N (input) INTEGER
The order of the matrix A. N >= 0.
A (input/output) COMPLEX array, dimension (LDA,N)
On entry, the block diagonal matrix D and the multipliers used to obtain the fac-
tor U or L as computed by CHETRF.
On exit, if INFO = 0, the (Hermitian) 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 CHETRF.
WORK (workspace) COMPLEX 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
LAPACK version 3.0 15 June 2000 CHETRI(l)