1DSYTRI(1)                LAPACK routine (version 3.2)                DSYTRI(1)
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NAME

6       DSYTRI  -  computes the inverse of a real symmetric indefinite matrix A
7       using the factorization A = U*D*U**T or A = L*D*L**T computed by DSYTRF
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SYNOPSIS

10       SUBROUTINE DSYTRI( 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           DOUBLE         PRECISION A( LDA, * ), WORK( * )
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PURPOSE

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

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