LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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sppcon.f File Reference

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Functions/Subroutines

subroutine sppcon (UPLO, N, AP, ANORM, RCOND, WORK, IWORK, INFO)
 SPPCON

Function/Subroutine Documentation

subroutine sppcon ( character  UPLO,
integer  N,
real, dimension( * )  AP,
real  ANORM,
real  RCOND,
real, dimension( * )  WORK,
integer, dimension( * )  IWORK,
integer  INFO 
)

SPPCON

Download SPPCON + dependencies [TGZ] [ZIP] [TXT]
Purpose: 
 SPPCON estimates the reciprocal of the condition number (in the
 1-norm) of a real symmetric positive definite packed matrix using
 the Cholesky factorization A = U**T*U or A = L*L**T computed by
 SPPTRF.

 An estimate is obtained for norm(inv(A)), and the reciprocal of the
 condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
Parameters:
[in]UPLO
          UPLO is CHARACTER*1
          = 'U':  Upper triangle of A is stored;
          = 'L':  Lower triangle of A is stored.
[in]N
          N is INTEGER
          The order of the matrix A.  N >= 0.
[in]AP
          AP is REAL array, dimension (N*(N+1)/2)
          The triangular factor U or L from the Cholesky factorization
          A = U**T*U or A = L*L**T, packed columnwise in a linear
          array.  The j-th column of U or L is stored in the array AP
          as follows:
          if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
[in]ANORM
          ANORM is REAL
          The 1-norm (or infinity-norm) of the symmetric matrix A.
[out]RCOND
          RCOND is REAL
          The reciprocal of the condition number of the matrix A,
          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
          estimate of the 1-norm of inv(A) computed in this routine.
[out]WORK
          WORK is REAL array, dimension (3*N)
[out]IWORK
          IWORK is INTEGER array, dimension (N)
[out]INFO
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011

Definition at line 119 of file sppcon.f.

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