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ZLAREF(l)			       )			     ZLAREF(l)

NAME
       ZLAREF  - applie	one or several Householder reflectors of size 3	to one
       or two matrices (if column is specified)	on either their	rows  or  col-
       umns

SYNOPSIS
       SUBROUTINE ZLAREF( TYPE,	 A,  LDA,  WANTZ, Z, LDZ, BLOCK, IROW1,	ICOL1,
			  ISTART, ISTOP, ITMP1,	ITMP2, LILOZ, LIHIZ, VECS, V2,
			  V3, T1, T2, T3 )

	   LOGICAL	  BLOCK, WANTZ

	   CHARACTER	  TYPE

	   INTEGER	  ICOL1, IROW1,	ISTART,	ISTOP, ITMP1, ITMP2, LDA, LDZ,
			  LIHIZ, LILOZ

	   COMPLEX*16	  T1, T2, T3, V2, V3

	   COMPLEX*16	  A( LDA, * ), VECS( * ), Z( LDZ, * )

PURPOSE
       ZLAREF applies one or several Householder reflectors of size 3  to  one
       or  two	matrices (if column is specified) on either their rows or col-
       umns.

ARGUMENTS
       TYPE    (global input) CHARACTER*1
	       If 'R': Apply reflectors	to the rows of the matrix (apply  from
	       left)  Otherwise: Apply reflectors to the columns of the	matrix
	       Unchanged on exit.

       A       (global input/output) COMPLEX*16	array, (LDA,*)
	       On entry, the matrix to receive the reflections.	  The  updated
	       matrix on exit.

       LDA     (local input) INTEGER
	       On entry, the leading dimension of A.  Unchanged	on exit.

       WANTZ   (global input) LOGICAL
	       If  .TRUE., then	apply any column reflections to	Z as well.  If
	       .FALSE.,	then do	no additional work on Z.

       Z       (global input/output) COMPLEX*16	array, (LDZ,*)
	       On entry, the second  matrix  to	 receive  column  reflections.
	       This is changed only if WANTZ is	set.

       LDZ     (local input) INTEGER
	       On entry, the leading dimension of Z.  Unchanged	on exit.

       BLOCK   (global input) LOGICAL
	       If .TRUE., then apply several reflectors	at once	and read their
	       data from the VECS array.  If .FALSE., apply the	single reflec-
	       tor given by V2,	V3, T1,	T2, and	T3.

       IROW1   (local input/output) INTEGER
	       On entry, the local row element of A.  Undefined	on output.

       ICOL1   (local input/output) INTEGER
	       On entry, the local column element of A.	 Undefined on output.

       ISTART  (global input) INTEGER
	       Specifies the "number" of the first reflector.  This is used as
	       an index	into VECS if BLOCK is set.  ISTART is ignored if BLOCK
	       is .FALSE..

       ISTOP   (global input) INTEGER
	       Specifies  the "number" of the last reflector.  This is used as
	       an index	into VECS if BLOCK is set.  ISTOP is ignored if	 BLOCK
	       is .FALSE..

       ITMP1   (local input) INTEGER
	       Starting	 range into A.	For rows, this is the local first col-
	       umn.  For columns, this is the local first row.

       ITMP2   (local input) INTEGER
	       Ending range into A.  For rows, this is the local last  column.
	       For columns, this is the	local last row.

	       LILOZ  LIHIZ    (local input) INTEGER These serve the same pur-
	       pose as ITMP1,ITMP2 but for Z when WANTZ	is set.

       VECS    (global input) COMPLEX*16 array of size 3*N (matrix size)
	       This holds the size 3 reflectors	one after another and this  is
	       only accessed when BLOCK	is .TRUE.

	       V2 V3 T1	T2 T3	   (global input/output) COMPLEX*16 This holds
	       information on a	single size 3  Householder  reflector  and  is
	       read  when  BLOCK  is  .FALSE.,	and  overwritten when BLOCK is
	       .TRUE.

FURTHER	DETAILS
       Implemented by:	M. Fahey, May 28, 1999

ScaLAPACK version 1.7		13 August 2001			     ZLAREF(l)

NAME | SYNOPSIS | PURPOSE | ARGUMENTS | FURTHER DETAILS

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