ZLAED0(l)								 )								 ZLAED0(l)

NAME

       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

SYNOPSIS

       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, * )

PURPOSE

       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 mul-
	      tiplies 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).

LAPACK version 3.0						   15 June 2000 							 ZLAED0(l)