CXML
        	    
LAPACK version 3.0
zlaed0(3)

PURPOSE
  ZLAED0 - the divide and conquer method, ZLAED0 computes all eigenvalues of
  a symmetric tridiagonal matrix which is one diagonal block of those from
  reducing a dense or band Hermitian matrix and corresponding eigenvectors of
  the dense or band matrix

SYNTAX
  SUBROUTINE ZLAED0( QSIZ, N, D, E, Q, LDQ, QSTORE, LDQS, RWORK, IWORK, INFO
		     )

      INTEGER	     INFO, LDQ, LDQS, N, QSIZ

      INTEGER	     IWORK( * )

      DOUBLE	     PRECISION D( * ), E( * ), RWORK( * )

      COMPLEX*16     Q( LDQ, * ), QSTORE( LDQS, * )

DESCRIPTION
  Using the divide and conquer method, ZLAED0 computes all eigenvalues of a
  symmetric tridiagonal matrix which is one diagonal block of those from
  reducing a dense or band Hermitian matrix and corresponding eigenvectors of
  the dense or band matrix.

ARGUMENTS
  QSIZ	 (input) INTEGER
	 The dimension of the unitary matrix used to reduce the full matrix
	 to tridiagonal form.  QSIZ >= N if ICOMPQ = 1.

  N	 (input) INTEGER
	 The dimension of the symmetric tridiagonal matrix.  N >= 0.

  D	 (input/output) DOUBLE PRECISION array, dimension (N)
	 On entry, the diagonal elements of the tridiagonal matrix.  On exit,
	 the eigenvalues in ascending order.

  E	 (input/output) DOUBLE PRECISION array, dimension (N-1)
	 On entry, the off-diagonal elements of the tridiagonal matrix.	 On
	 exit, E has been destroyed.

  Q	 (input/output) COMPLEX*16 array, dimension (LDQ,N)
	 On entry, Q must contain an QSIZ x N matrix whose columns unitarily
	 orthonormal. It is a part of the unitary matrix that reduces the
	 full dense Hermitian matrix to a (reducible) symmetric tridiagonal
	 matrix.

  LDQ	 (input) INTEGER
	 The leading dimension of the array Q.	LDQ >= max(1,N).

  IWORK	 (workspace) INTEGER array,
	 the dimension of IWORK must be at least 6 + 6*N + 5*N*lg N ( lg( N )
	 = smallest integer k such that 2^k >= N )

  RWORK	 (workspace) DOUBLE PRECISION array,
	 dimension (1 + 3*N + 2*N*lg N + 3*N**2) ( lg( N ) = smallest integer
	 k such that 2^k >= N )

	 QSTORE (workspace) COMPLEX*16 array, dimension (LDQS, N) Used to
	 store parts of the eigenvector matrix when the updating matrix
	 multiplies take place.

  LDQS	 (input) INTEGER
	 The leading dimension of the array QSTORE.  LDQS >= max(1,N).

  INFO	 (output) INTEGER
	 = 0:  successful exit.
	 < 0:  if INFO = -i, the i-th argument had an illegal value.
	 > 0:  The algorithm failed to compute an eigenvalue while working on
	 the submatrix lying in rows and columns INFO/(N+1) through
	 mod(INFO,N+1).