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

6       SGECON  - estimates the reciprocal of the condition number of a general
7       real matrix A, in either the 1-norm or the infinity-norm, using the  LU
8       factorization computed by SGETRF
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SYNOPSIS

11       SUBROUTINE SGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO )
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13           CHARACTER      NORM
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15           INTEGER        INFO, LDA, N
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17           REAL           ANORM, RCOND
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19           INTEGER        IWORK( * )
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21           REAL           A( LDA, * ), WORK( * )
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PURPOSE

24       SGECON  estimates  the  reciprocal of the condition number of a general
25       real matrix A, in either the 1-norm or the infinity-norm, using the  LU
26       factorization   computed  by  SGETRF.   An  estimate  is  obtained  for
27       norm(inv(A)), and the reciprocal of the condition number is computed as
28          RCOND = 1 / ( norm(A) * norm(inv(A)) ).
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ARGUMENTS

31       NORM    (input) CHARACTER*1
32               Specifies whether the 1-norm condition number or the  infinity-
33               norm condition number is required:
34               = '1' or 'O':  1-norm;
35               = 'I':         Infinity-norm.
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37       N       (input) INTEGER
38               The order of the matrix A.  N >= 0.
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40       A       (input) REAL array, dimension (LDA,N)
41               The  factors  L  and U from the factorization A = P*L*U as com‐
42               puted by SGETRF.
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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       ANORM   (input) REAL
48               If NORM = '1' or 'O', the 1-norm of the original matrix A.   If
49               NORM = 'I', the infinity-norm of the original matrix A.
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51       RCOND   (output) REAL
52               The  reciprocal  of  the condition number of the matrix A, com‐
53               puted as RCOND = 1/(norm(A) * norm(inv(A))).
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55       WORK    (workspace) REAL array, dimension (4*N)
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57       IWORK   (workspace) INTEGER array, dimension (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                       SGECON(1)
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