zptcon.f(3)

NAME
zptcon.f -

SYNOPSIS

  Functions/Subroutines
subroutine ZPTCON (N, D, E, ANORM, RCOND, RWORK, INFO)
ZPTCON

Function/Subroutine Documentation

  subroutine ZPTCON (INTEGERN, DOUBLE PRECISION, dimension( * )D, COMPLEX*16, dimension( * )E, DOUBLE PRECISIONANORM, DOUBLE PRECISIONRCOND, DOUBLE PRECISION, dimension( * )RWORK, INTEGERINFO)

ZPTCON

Purpose:

     ZPTCON computes the reciprocal of the condition number (in the
     1-norm) of a complex Hermitian positive definite tridiagonal matrix
     using the factorization A = L*D*L**H or A = U**H*D*U computed by
     ZPTTRF.
     Norm(inv(A)) is computed by a direct method, and the reciprocal of
     the condition number is computed as
                      RCOND = 1 / (ANORM * norm(inv(A))).

Parameters:
    N

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

    D

              D is DOUBLE PRECISION array, dimension (N)
              The n diagonal elements of the diagonal matrix D from the
              factorization of A, as computed by ZPTTRF.

    E

              E is COMPLEX*16 array, dimension (N-1)
              The (n-1) off-diagonal elements of the unit bidiagonal factor
              U or L from the factorization of A, as computed by ZPTTRF.

    ANORM

              ANORM is DOUBLE PRECISION
              The 1-norm of the original 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 the
              1-norm of inv(A) computed in this routine.

    RWORK

              RWORK is DOUBLE PRECISION array, dimension (N)

    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

Further Details:

      The method used is described in Nicholas J. Higham, "Efficient
      Algorithms for Computing the Condition Number of a Tridiagonal
      Matrix", SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.

Definition at line 120 of file zptcon.f'.

Author

Generated automatically by Doxygen for LAPACK from the source code'.