1CHETRI(1)                LAPACK routine (version 3.2)                CHETRI(1)
2
3
4

NAME

6       CHETRI  - computes the inverse of a complex Hermitian indefinite matrix
7       A using the factorization A = U*D*U**H or  A  =  L*D*L**H  computed  by
8       CHETRF
9

SYNOPSIS

11       SUBROUTINE CHETRI( UPLO, N, A, LDA, IPIV, WORK, INFO )
12
13           CHARACTER      UPLO
14
15           INTEGER        INFO, LDA, N
16
17           INTEGER        IPIV( * )
18
19           COMPLEX        A( LDA, * ), WORK( * )
20

PURPOSE

22       CHETRI  computes the inverse of a complex Hermitian indefinite matrix A
23       using the factorization A =  U*D*U**H  or  A  =  L*D*L**H  computed  by
24       CHETRF.
25

ARGUMENTS

27       UPLO    (input) CHARACTER*1
28               Specifies  whether  the details of the factorization are stored
29               as an upper or lower triangular matrix.  = 'U':  Upper triangu‐
30               lar, form is A = U*D*U**H;
31               = 'L':  Lower triangular, form is A = L*D*L**H.
32
33       N       (input) INTEGER
34               The order of the matrix A.  N >= 0.
35
36       A       (input/output) COMPLEX array, dimension (LDA,N)
37               On  entry, the block diagonal matrix D and the multipliers used
38               to obtain the factor U or L as computed by CHETRF.  On exit, if
39               INFO  =  0, the (Hermitian) inverse of the original matrix.  If
40               UPLO = 'U', the upper triangular part of the inverse is  formed
41               and the part of A below the diagonal is not referenced; if UPLO
42               = 'L' the lower triangular part of the inverse  is  formed  and
43               the part of A above the diagonal is not referenced.
44
45       LDA     (input) INTEGER
46               The leading dimension of the array A.  LDA >= max(1,N).
47
48       IPIV    (input) INTEGER array, dimension (N)
49               Details  of  the  interchanges  and the block structure of D as
50               determined by CHETRF.
51
52       WORK    (workspace) COMPLEX array, dimension (N)
53
54       INFO    (output) INTEGER
55               = 0: successful exit
56               < 0: if INFO = -i, the i-th argument had an illegal value
57               > 0: if INFO = i, D(i,i) = 0; the matrix is  singular  and  its
58               inverse could not be computed.
59
60
61
62 LAPACK routine (version 3.2)    November 2008                       CHETRI(1)
Impressum