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

6       DPOCON  -  estimates  the  reciprocal  of  the condition number (in the
7       1-norm) of a real symmetric positive definite matrix using the Cholesky
8       factorization A = U**T*U or A = L*L**T computed by DPOTRF
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SYNOPSIS

11       SUBROUTINE DPOCON( UPLO, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO )
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13           CHARACTER      UPLO
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15           INTEGER        INFO, LDA, N
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17           DOUBLE         PRECISION ANORM, RCOND
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19           INTEGER        IWORK( * )
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21           DOUBLE         PRECISION A( LDA, * ), WORK( * )
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PURPOSE

24       DPOCON estimates the reciprocal of the condition number (in the 1-norm)
25       of a real symmetric positive definite matrix using the Cholesky factor‐
26       ization  A  =  U**T*U or A = L*L**T computed by DPOTRF.  An estimate is
27       obtained for norm(inv(A)), and the reciprocal of the  condition  number
28       is computed as RCOND = 1 / (ANORM * norm(inv(A))).
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ARGUMENTS

31       UPLO    (input) CHARACTER*1
32               = 'U':  Upper triangle of A is stored;
33               = 'L':  Lower triangle of A is stored.
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35       N       (input) INTEGER
36               The order of the matrix A.  N >= 0.
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38       A       (input) DOUBLE PRECISION array, dimension (LDA,N)
39               The  triangular factor U or L from the Cholesky factorization A
40               = U**T*U or A = L*L**T, as computed by DPOTRF.
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42       LDA     (input) INTEGER
43               The leading dimension of the array A.  LDA >= max(1,N).
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45       ANORM   (input) DOUBLE PRECISION
46               The 1-norm (or infinity-norm) of the symmetric matrix A.
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48       RCOND   (output) DOUBLE PRECISION
49               The reciprocal of the condition number of the  matrix  A,  com‐
50               puted  as  RCOND = 1/(ANORM * AINVNM), where AINVNM is an esti‐
51               mate of the 1-norm of inv(A) computed in this routine.
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53       WORK    (workspace) DOUBLE PRECISION array, dimension (3*N)
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55       IWORK   (workspace) INTEGER array, dimension (N)
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57       INFO    (output) INTEGER
58               = 0:  successful exit
59               < 0:  if INFO = -i, the i-th argument had an illegal value
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63 LAPACK routine (version 3.2)    November 2008                       DPOCON(1)
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