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SUBROUTINE <a name="DLAEDA.1"></a><a href="dlaeda.f.html#DLAEDA.1">DLAEDA</a>( N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR,
$ GIVCOL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> -- LAPACK routine (version 3.1) --
</span><span class="comment">*</span><span class="comment"> Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
</span><span class="comment">*</span><span class="comment"> November 2006
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> .. Scalar Arguments ..
</span> INTEGER CURLVL, CURPBM, INFO, N, TLVLS
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Array Arguments ..
</span> INTEGER GIVCOL( 2, * ), GIVPTR( * ), PERM( * ),
$ PRMPTR( * ), QPTR( * )
DOUBLE PRECISION GIVNUM( 2, * ), Q( * ), Z( * ), ZTEMP( * )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Purpose
</span><span class="comment">*</span><span class="comment"> =======
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> <a name="DLAEDA.20"></a><a href="dlaeda.f.html#DLAEDA.1">DLAEDA</a> computes the Z vector corresponding to the merge step in the
</span><span class="comment">*</span><span class="comment"> CURLVLth step of the merge process with TLVLS steps for the CURPBMth
</span><span class="comment">*</span><span class="comment"> problem.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Arguments
</span><span class="comment">*</span><span class="comment"> =========
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> N (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The dimension of the symmetric tridiagonal matrix. N >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> TLVLS (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The total number of merging levels in the overall divide and
</span><span class="comment">*</span><span class="comment"> conquer tree.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> CURLVL (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The current level in the overall merge routine,
</span><span class="comment">*</span><span class="comment"> 0 <= curlvl <= tlvls.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> CURPBM (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The current problem in the current level in the overall
</span><span class="comment">*</span><span class="comment"> merge routine (counting from upper left to lower right).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> PRMPTR (input) INTEGER array, dimension (N lg N)
</span><span class="comment">*</span><span class="comment"> Contains a list of pointers which indicate where in PERM a
</span><span class="comment">*</span><span class="comment"> level's permutation is stored. PRMPTR(i+1) - PRMPTR(i)
</span><span class="comment">*</span><span class="comment"> indicates the size of the permutation and incidentally the
</span><span class="comment">*</span><span class="comment"> size of the full, non-deflated problem.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> PERM (input) INTEGER array, dimension (N lg N)
</span><span class="comment">*</span><span class="comment"> Contains the permutations (from deflation and sorting) to be
</span><span class="comment">*</span><span class="comment"> applied to each eigenblock.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> GIVPTR (input) INTEGER array, dimension (N lg N)
</span><span class="comment">*</span><span class="comment"> Contains a list of pointers which indicate where in GIVCOL a
</span><span class="comment">*</span><span class="comment"> level's Givens rotations are stored. GIVPTR(i+1) - GIVPTR(i)
</span><span class="comment">*</span><span class="comment"> indicates the number of Givens rotations.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> GIVCOL (input) INTEGER array, dimension (2, N lg N)
</span><span class="comment">*</span><span class="comment"> Each pair of numbers indicates a pair of columns to take place
</span><span class="comment">*</span><span class="comment"> in a Givens rotation.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> GIVNUM (input) DOUBLE PRECISION array, dimension (2, N lg N)
</span><span class="comment">*</span><span class="comment"> Each number indicates the S value to be used in the
</span><span class="comment">*</span><span class="comment"> corresponding Givens rotation.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Q (input) DOUBLE PRECISION array, dimension (N**2)
</span><span class="comment">*</span><span class="comment"> Contains the square eigenblocks from previous levels, the
</span><span class="comment">*</span><span class="comment"> starting positions for blocks are given by QPTR.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> QPTR (input) INTEGER array, dimension (N+2)
</span><span class="comment">*</span><span class="comment"> Contains a list of pointers which indicate where in Q an
</span><span class="comment">*</span><span class="comment"> eigenblock is stored. SQRT( QPTR(i+1) - QPTR(i) ) indicates
</span><span class="comment">*</span><span class="comment"> the size of the block.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Z (output) DOUBLE PRECISION array, dimension (N)
</span><span class="comment">*</span><span class="comment"> On output this vector contains the updating vector (the last
</span><span class="comment">*</span><span class="comment"> row of the first sub-eigenvector matrix and the first row of
</span><span class="comment">*</span><span class="comment"> the second sub-eigenvector matrix).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> ZTEMP (workspace) DOUBLE PRECISION array, dimension (N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> INFO (output) INTEGER
</span><span class="comment">*</span><span class="comment"> = 0: successful exit.
</span><span class="comment">*</span><span class="comment"> < 0: if INFO = -i, the i-th argument had an illegal value.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Further Details
</span><span class="comment">*</span><span class="comment"> ===============
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Based on contributions by
</span><span class="comment">*</span><span class="comment"> Jeff Rutter, Computer Science Division, University of California
</span><span class="comment">*</span><span class="comment"> at Berkeley, USA
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> .. Parameters ..
</span> DOUBLE PRECISION ZERO, HALF, ONE
PARAMETER ( ZERO = 0.0D0, HALF = 0.5D0, ONE = 1.0D0 )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Local Scalars ..
</span> INTEGER BSIZ1, BSIZ2, CURR, I, K, MID, PSIZ1, PSIZ2,
$ PTR, ZPTR1
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. External Subroutines ..
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