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

6       SSYCON  -  estimates  the  reciprocal  of  the condition number (in the
7       1-norm) of a real symmetric  matrix  A  using  the  factorization  A  =
8       U*D*U**T or A = L*D*L**T computed by SSYTRF
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SYNOPSIS

11       SUBROUTINE SSYCON( UPLO,  N,  A,  LDA, IPIV, ANORM, RCOND, WORK, IWORK,
12                          INFO )
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14           CHARACTER      UPLO
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16           INTEGER        INFO, LDA, N
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18           REAL           ANORM, RCOND
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20           INTEGER        IPIV( * ), IWORK( * )
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22           REAL           A( LDA, * ), WORK( * )
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PURPOSE

25       SSYCON estimates the reciprocal of the condition number (in the 1-norm)
26       of  a real symmetric matrix A using the factorization A = U*D*U**T or A
27       =  L*D*L**T  computed  by  SSYTRF.   An  estimate   is   obtained   for
28       norm(inv(A)), and the reciprocal of the condition number is computed as
29       RCOND = 1 / (ANORM * norm(inv(A))).
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ARGUMENTS

32       UPLO    (input) CHARACTER*1
33               Specifies whether the details of the factorization  are  stored
34               as an upper or lower triangular matrix.  = 'U':  Upper triangu‐
35               lar, form is A = U*D*U**T;
36               = 'L':  Lower triangular, form is A = L*D*L**T.
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38       N       (input) INTEGER
39               The order of the matrix A.  N >= 0.
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41       A       (input) REAL array, dimension (LDA,N)
42               The block diagonal matrix D and the multipliers used to  obtain
43               the factor U or L as computed by SSYTRF.
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45       LDA     (input) INTEGER
46               The leading dimension of the array A.  LDA >= max(1,N).
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48       IPIV    (input) INTEGER array, dimension (N)
49               Details  of  the  interchanges  and the block structure of D as
50               determined by SSYTRF.
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52       ANORM   (input) REAL
53               The 1-norm of the original matrix A.
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55       RCOND   (output) REAL
56               The reciprocal of the condition number of the  matrix  A,  com‐
57               puted  as  RCOND = 1/(ANORM * AINVNM), where AINVNM is an esti‐
58               mate of the 1-norm of inv(A) computed in this routine.
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60       WORK    (workspace) REAL array, dimension (2*N)
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62       IWORK    (workspace) INTEGER array, dimension (N)
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64       INFO    (output) INTEGER
65               = 0:  successful exit
66               < 0:  if INFO = -i, the i-th argument had an illegal value
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70 LAPACK routine (version 3.2)    November 2008                       SSYCON(1)
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