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

6       CHPCON  - estimates the reciprocal of the condition number of a complex
7       Hermitian packed matrix A using the factorization A = U*D*U**H or  A  =
8       L*D*L**H computed by CHPTRF
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SYNOPSIS

11       SUBROUTINE CHPCON( UPLO, N, AP, IPIV, ANORM, RCOND, WORK, INFO )
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13           CHARACTER      UPLO
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15           INTEGER        INFO, N
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17           REAL           ANORM, RCOND
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19           INTEGER        IPIV( * )
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21           COMPLEX        AP( * ), WORK( * )
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PURPOSE

24       CHPCON  estimates  the  reciprocal of the condition number of a complex
25       Hermitian packed matrix A using the factorization A = U*D*U**H or  A  =
26       L*D*L**H computed by CHPTRF.  An estimate is obtained for norm(inv(A)),
27       and the reciprocal of the condition number is computed as RCOND =  1  /
28       (ANORM * norm(inv(A))).
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ARGUMENTS

31       UPLO    (input) CHARACTER*1
32               Specifies  whether  the details of the factorization are stored
33               as an upper or lower triangular matrix.  = 'U':  Upper triangu‐
34               lar, form is A = U*D*U**H;
35               = 'L':  Lower triangular, form is A = L*D*L**H.
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37       N       (input) INTEGER
38               The order of the matrix A.  N >= 0.
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40       AP      (input) COMPLEX array, dimension (N*(N+1)/2)
41               The  block diagonal matrix D and the multipliers used to obtain
42               the factor U or L as computed by CHPTRF,  stored  as  a  packed
43               triangular matrix.
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45       IPIV    (input) INTEGER array, dimension (N)
46               Details  of  the  interchanges  and the block structure of D as
47               determined by CHPTRF.
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49       ANORM   (input) REAL
50               The 1-norm of the original matrix A.
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52       RCOND   (output) REAL
53               The reciprocal of the condition number of the  matrix  A,  com‐
54               puted  as  RCOND = 1/(ANORM * AINVNM), where AINVNM is an esti‐
55               mate of the 1-norm of inv(A) computed in this routine.
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57       WORK    (workspace) COMPLEX array, dimension (2*N)
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59       INFO    (output) INTEGER
60               = 0:  successful exit
61               < 0:  if INFO = -i, the i-th argument had an illegal value
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65 LAPACK routine (version 3.2)    November 2008                       CHPCON(1)
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