1ZSYTRI(1)                LAPACK routine (version 3.1)                ZSYTRI(1)
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NAME

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

10       SUBROUTINE ZSYTRI( UPLO, N, A, LDA, IPIV, WORK, INFO )
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12           CHARACTER      UPLO
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14           INTEGER        INFO, LDA, N
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16           INTEGER        IPIV( * )
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18           COMPLEX*16     A( LDA, * ), WORK( * )
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PURPOSE

21       ZSYTRI computes the inverse of a complex symmetric indefinite matrix  A
22       using  the  factorization  A  =  U*D*U**T  or  A = L*D*L**T computed by
23       ZSYTRF.
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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**T;
31               = 'L':  Lower triangular, form is A = L*D*L**T.
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33       N       (input) INTEGER
34               The order of the matrix A.  N >= 0.
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36       A       (input/output) COMPLEX*16 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 ZSYTRF.
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40               On  exit,  if INFO = 0, the (symmetric) inverse of the original
41               matrix.  If UPLO =  'U',  the  upper  triangular  part  of  the
42               inverse  is  formed and the part of A below the diagonal is not
43               referenced; if UPLO = 'L' the  lower  triangular  part  of  the
44               inverse  is  formed and the part of A above the diagonal is not
45               referenced.
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47       LDA     (input) INTEGER
48               The leading dimension of the array A.  LDA >= max(1,N).
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50       IPIV    (input) INTEGER array, dimension (N)
51               Details of the interchanges and the block  structure  of  D  as
52               determined by ZSYTRF.
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54       WORK    (workspace) COMPLEX*16 array, dimension (2*N)
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56       INFO    (output) INTEGER
57               = 0: successful exit
58               < 0: if INFO = -i, the i-th argument had an illegal value
59               >  0:  if  INFO = i, D(i,i) = 0; the matrix is singular and its
60               inverse could not be computed.
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64 LAPACK routine (version 3.1)    November 2006                       ZSYTRI(1)
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