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

6       SPPCON  -  the  reciprocal of the condition number (in the 1-norm) of a
7       real symmetric positive definite packed matrix using the Cholesky  fac‐
8       torization A = U**T*U or A = L*L**T computed by SPPTRF
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SYNOPSIS

11       SUBROUTINE SPPCON( UPLO, N, AP, ANORM, RCOND, WORK, IWORK, 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        IWORK( * )
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21           REAL           AP( * ), WORK( * )
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PURPOSE

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

33       UPLO    (input) CHARACTER*1
34               = 'U':  Upper triangle of A is stored;
35               = 'L':  Lower triangle of A is stored.
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37       N       (input) INTEGER
38               The order of the matrix A.  N >= 0.
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40       AP      (input) REAL array, dimension (N*(N+1)/2)
41               The triangular factor U or L from the Cholesky factorization  A
42               =  U**T*U  or  A = L*L**T, packed columnwise in a linear array.
43               The j-th column of U or L is stored in the array AP as follows:
44               if  UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j; if UPLO
45               = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
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47       ANORM   (input) REAL
48               The 1-norm (or infinity-norm) of the symmetric matrix A.
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50       RCOND   (output) REAL
51               The reciprocal of the condition number of the  matrix  A,  com‐
52               puted  as  RCOND = 1/(ANORM * AINVNM), where AINVNM is an esti‐
53               mate of the 1-norm of inv(A) computed in this routine.
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55       WORK    (workspace) REAL array, dimension (3*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 3.1)    November 2006                       SPPCON(1)
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