CXML
        	    
LAPACK version 3.0
cptcon(3)

PURPOSE
  CPTCON - compute 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 CPTTRF

SYNTAX
  SUBROUTINE CPTCON( N, D, E, ANORM, RCOND, RWORK, INFO )

      INTEGER	     INFO, N

      REAL	     ANORM, RCOND

      REAL	     D( * ), RWORK( * )

      COMPLEX	     E( * )

DESCRIPTION
  CPTCON 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 CPTTRF.
  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))).

ARGUMENTS
  N	  (input) INTEGER
	  The order of the matrix A.  N >= 0.

  D	  (input) REAL array, dimension (N)
	  The n diagonal elements of the diagonal matrix D from the
	  factorization of A, as computed by CPTTRF.

  E	  (input) COMPLEX 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 CPTTRF.

  ANORM	  (input) REAL
	  The 1-norm of the original matrix A.

  RCOND	  (output) REAL
	  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	  (workspace) REAL array, dimension (N)

  INFO	  (output) INTEGER
	  = 0:	successful exit
	  < 0:	if INFO = -i, the i-th argument had an illegal value

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.