1CTPCON(1)                LAPACK routine (version 3.1)                CTPCON(1)
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NAME

6       CTPCON  - the reciprocal of the condition number of a packed triangular
7       matrix A, in either the 1-norm or the infinity-norm
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SYNOPSIS

10       SUBROUTINE CTPCON( NORM, UPLO, DIAG, N, AP, RCOND, WORK, RWORK, INFO )
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12           CHARACTER      DIAG, NORM, UPLO
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14           INTEGER        INFO, N
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16           REAL           RCOND
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18           REAL           RWORK( * )
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20           COMPLEX        AP( * ), WORK( * )
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PURPOSE

23       CTPCON estimates the reciprocal of the condition  number  of  a  packed
24       triangular matrix A, in either the 1-norm or the infinity-norm.
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26       The norm of A is computed and an estimate is obtained for norm(inv(A)),
27       then the reciprocal of the condition number is computed as
28          RCOND = 1 / ( norm(A) * norm(inv(A)) ).
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ARGUMENTS

32       NORM    (input) CHARACTER*1
33               Specifies whether the 1-norm condition number or the  infinity-
34               norm condition number is required:
35               = '1' or 'O':  1-norm;
36               = 'I':         Infinity-norm.
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38       UPLO    (input) CHARACTER*1
39               = 'U':  A is upper triangular;
40               = 'L':  A is lower triangular.
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42       DIAG    (input) CHARACTER*1
43               = 'N':  A is non-unit triangular;
44               = 'U':  A is unit triangular.
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46       N       (input) INTEGER
47               The order of the matrix A.  N >= 0.
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49       AP      (input) COMPLEX array, dimension (N*(N+1)/2)
50               The  upper or lower triangular matrix A, packed columnwise in a
51               linear array.  The j-th column of A is stored in the  array  AP
52               as  follows:  if  UPLO  =  'U',  AP(i + (j-1)*j/2) = A(i,j) for
53               1<=i<=j; if UPLO = 'L', AP(i +  (j-1)*(2n-j)/2)  =  A(i,j)  for
54               j<=i<=n.   If  DIAG  =  'U', the diagonal elements of A are not
55               referenced and are assumed to be 1.
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57       RCOND   (output) REAL
58               The reciprocal of the condition number of the  matrix  A,  com‐
59               puted as RCOND = 1/(norm(A) * norm(inv(A))).
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61       WORK    (workspace) COMPLEX array, dimension (2*N)
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63       RWORK   (workspace) REAL array, dimension (N)
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65       INFO    (output) INTEGER
66               = 0:  successful exit
67               < 0:  if INFO = -i, the i-th argument had an illegal value
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71 LAPACK routine (version 3.1)    November 2006                       CTPCON(1)
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