dlaed0.f(3)							      LAPACK							       dlaed0.f(3)

NAME

       dlaed0.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dlaed0 (ICOMPQ, QSIZ, N, D, E, Q, LDQ, QSTORE, LDQS, WORK, IWORK, INFO)
	   DLAED0 used by sstedc. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the
	   divide and conquer method.

Function/Subroutine Documentation
   subroutine dlaed0 (integerICOMPQ, integerQSIZ, integerN, double precision, dimension( * )D, double precision, dimension( * )E, double
       precision, dimension( ldq, * )Q, integerLDQ, double precision, dimension( ldqs, * )QSTORE, integerLDQS, double precision, dimension( *
       )WORK, integer, dimension( * )IWORK, integerINFO)
       DLAED0 used by sstedc. Computes all eigenvalues and corresponding eigenvectors of an unreduced symmetric tridiagonal matrix using the
       divide and conquer method.

       Purpose:

	    DLAED0 computes all eigenvalues and corresponding eigenvectors of a
	    symmetric tridiagonal matrix using the divide and conquer method.

       Parameters:
	   ICOMPQ

		     ICOMPQ is INTEGER
		     = 0:  Compute eigenvalues only.
		     = 1:  Compute eigenvectors of original dense symmetric matrix
			   also.  On entry, Q contains the orthogonal matrix used
			   to reduce the original matrix to tridiagonal form.
		     = 2:  Compute eigenvalues and eigenvectors of tridiagonal
			   matrix.

	   QSIZ

		     QSIZ is INTEGER
		    The dimension of the orthogonal matrix used to reduce
		    the full matrix to tridiagonal form.  QSIZ >= N if ICOMPQ = 1.

	   N

		     N is INTEGER
		    The dimension of the symmetric tridiagonal matrix.	N >= 0.

	   D

		     D is DOUBLE PRECISION array, dimension (N)
		    On entry, the main diagonal of the tridiagonal matrix.
		    On exit, its eigenvalues.

	   E

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

	   Q

		     Q is DOUBLE PRECISION array, dimension (LDQ, N)
		    On entry, Q must contain an N-by-N orthogonal matrix.
		    If ICOMPQ = 0    Q is not referenced.
		    If ICOMPQ = 1    On entry, Q is a subset of the columns of the
				     orthogonal matrix used to reduce the full
				     matrix to tridiagonal form corresponding to
				     the subset of the full matrix which is being
				     decomposed at this time.
		    If ICOMPQ = 2    On entry, Q will be the identity matrix.
				     On exit, Q contains the eigenvectors of the
				     tridiagonal matrix.

	   LDQ

		     LDQ is INTEGER
		    The leading dimension of the array Q.  If eigenvectors are
		    desired, then  LDQ >= max(1,N).  In any case,  LDQ >= 1.

	   QSTORE

		     QSTORE is DOUBLE PRECISION array, dimension (LDQS, N)
		    Referenced only when ICOMPQ = 1.  Used to store parts of
		    the eigenvector matrix when the updating matrix multiplies
		    take place.

	   LDQS

		     LDQS is INTEGER
		    The leading dimension of the array QSTORE.	If ICOMPQ = 1,
		    then  LDQS >= max(1,N).  In any case,  LDQS >= 1.

	   WORK

		     WORK is DOUBLE PRECISION array,
		    If ICOMPQ = 0 or 1, the dimension of WORK must be at least
				1 + 3*N + 2*N*lg N + 3*N**2
				( lg( N ) = smallest integer k
					    such that 2^k >= N )
		    If ICOMPQ = 2, the dimension of WORK must be at least
				4*N + N**2.

	   IWORK

		     IWORK is INTEGER array,
		    If ICOMPQ = 0 or 1, 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 )
		    If ICOMPQ = 2, the dimension of IWORK must be at least
				   3 + 5*N.

	   INFO

		     INFO is 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).

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Contributors:
	   Jeff Rutter, Computer Science Division, University of California at Berkeley, USA

       Definition at line 172 of file dlaed0.f.

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

Version 3.4.2							  Tue Sep 25 2012						       dlaed0.f(3)