DPOCON estimates the reciprocal of the condition number (in the


 1-norm) of a real symmetric positive definite matrix using the


 Cholesky factorization A = U**T*U or A = L*L**T computed by DPOTRF.


 An estimate is obtained for norm(inv(A)), and the reciprocal of the


 condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).

UPLO

          UPLO is CHARACTER*1


          = 'U':  Upper triangle of A is stored;


          = 'L':  Lower triangle of A is stored.

N

          N is INTEGER


          The order of the matrix A.  N >= 0.

A

          A is DOUBLE PRECISION array, dimension (LDA,N)


          The triangular factor U or L from the Cholesky factorization


          A = U**T*U or A = L*L**T, as computed by DPOTRF.

LDA

          LDA is INTEGER


          The leading dimension of the array A.  LDA >= max(1,N).

ANORM

          ANORM is DOUBLE PRECISION


          The 1-norm (or infinity-norm) of the symmetric matrix A.

RCOND

          RCOND is DOUBLE PRECISION


          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.

WORK

          WORK is DOUBLE PRECISION array, dimension (3*N)

IWORK

          IWORK is INTEGER array, dimension (N)

INFO

          INFO is INTEGER


          = 0:  successful exit


          < 0:  if INFO = -i, the i-th argument had an illegal value

Univ. of Tennessee

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NAG Ltd.

November 2011