SLAEDA(l)								 )								 SLAEDA(l)

NAME

       SLAEDA  -  compute the Z vector corresponding to the merge step in the CURLVLth step of the merge process with TLVLS steps for the CURPBMth
       problem

SYNOPSIS

       SUBROUTINE SLAEDA( N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR, GIVCOL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO )

	   INTEGER	  CURLVL, CURPBM, INFO, N, TLVLS

	   INTEGER	  GIVCOL( 2, * ), GIVPTR( * ), PERM( * ), PRMPTR( * ), QPTR( * )

	   REAL 	  GIVNUM( 2, * ), Q( * ), Z( * ), ZTEMP( * )

PURPOSE

       SLAEDA computes the Z vector corresponding to the merge step in the CURLVLth step of the merge process with TLVLS steps	for  the  CURPBMth
       problem.

ARGUMENTS

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

       TLVLS  (input) INTEGER
	      The total number of merging levels in the overall divide and conquer tree.

	      CURLVL (input) INTEGER The current level in the overall merge routine, 0 <= curlvl <= tlvls.

	      CURPBM  (input)  INTEGER	The  current  problem in the current level in the overall merge routine (counting from upper left to lower
	      right).

	      PRMPTR (input) INTEGER array, dimension (N lg N) Contains a list of pointers which indicate where in PERM a level's  permutation	is
	      stored.  PRMPTR(i+1) - PRMPTR(i) indicates the size of the permutation and incidentally the size of the full, non-deflated problem.

       PERM   (input) INTEGER array, dimension (N lg N)
	      Contains the permutations (from deflation and sorting) to be applied to each eigenblock.

	      GIVPTR  (input)  INTEGER array, dimension (N lg N) Contains a list of pointers which indicate where in GIVCOL a level's Givens rota-
	      tions are stored.  GIVPTR(i+1) - GIVPTR(i) indicates the number of Givens rotations.

	      GIVCOL (input) INTEGER array, dimension (2, N lg N) Each pair of numbers indicates a pair of columns to take place in a Givens rota-
	      tion.

	      GIVNUM (input) REAL array, dimension (2, N lg N) Each number indicates the S value to be used in the corresponding Givens rotation.

       Q      (input) REAL array, dimension (N**2)
	      Contains the square eigenblocks from previous levels, the starting positions for blocks are given by QPTR.

       QPTR   (input) INTEGER array, dimension (N+2)
	      Contains	a  list  of pointers which indicate where in Q an eigenblock is stored.  SQRT( QPTR(i+1) - QPTR(i) ) indicates the size of
	      the block.

       Z      (output) REAL array, dimension (N)
	      On output this vector contains the updating vector (the last row of the first sub-eigenvector matrix and the first row of the second
	      sub-eigenvector matrix).

       ZTEMP  (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

       Based on contributions by
	  Jeff Rutter, Computer Science Division, University of California
	  at Berkeley, USA

LAPACK version 3.0						   15 June 2000 							 SLAEDA(l)