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*> \brief \b SLATZM
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download SLATZM + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/slatzm.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/slatzm.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/slatzm.f">
*> [TXT]</a>
*> \endhtmlonly
*
* Definition:
* ===========
*
* SUBROUTINE SLATZM( SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK )
*
* .. Scalar Arguments ..
* CHARACTER SIDE
* INTEGER INCV, LDC, M, N
* REAL TAU
* ..
* .. Array Arguments ..
* REAL C1( LDC, * ), C2( LDC, * ), V( * ), WORK( * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> This routine is deprecated and has been replaced by routine SORMRZ.
*>
*> SLATZM applies a Householder matrix generated by STZRQF to a matrix.
*>
*> Let P = I - tau*u*u**T, u = ( 1 ),
*> ( v )
*> where v is an (m-1) vector if SIDE = 'L', or a (n-1) vector if
*> SIDE = 'R'.
*>
*> If SIDE equals 'L', let
*> C = [ C1 ] 1
*> [ C2 ] m-1
*> n
*> Then C is overwritten by P*C.
*>
*> If SIDE equals 'R', let
*> C = [ C1, C2 ] m
*> 1 n-1
*> Then C is overwritten by C*P.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] SIDE
*> \verbatim
*> SIDE is CHARACTER*1
*> = 'L': form P * C
*> = 'R': form C * P
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*> M is INTEGER
*> The number of rows of the matrix C.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> The number of columns of the matrix C.
*> \endverbatim
*>
*> \param[in] V
*> \verbatim
*> V is REAL array, dimension
*> (1 + (M-1)*abs(INCV)) if SIDE = 'L'
*> (1 + (N-1)*abs(INCV)) if SIDE = 'R'
*> The vector v in the representation of P. V is not used
*> if TAU = 0.
*> \endverbatim
*>
*> \param[in] INCV
*> \verbatim
*> INCV is INTEGER
*> The increment between elements of v. INCV <> 0
*> \endverbatim
*>
*> \param[in] TAU
*> \verbatim
*> TAU is REAL
*> The value tau in the representation of P.
*> \endverbatim
*>
*> \param[in,out] C1
*> \verbatim
*> C1 is REAL array, dimension
*> (LDC,N) if SIDE = 'L'
*> (M,1) if SIDE = 'R'
*> On entry, the n-vector C1 if SIDE = 'L', or the m-vector C1
*> if SIDE = 'R'.
*>
*> On exit, the first row of P*C if SIDE = 'L', or the first
*> column of C*P if SIDE = 'R'.
*> \endverbatim
*>
*> \param[in,out] C2
*> \verbatim
*> C2 is REAL array, dimension
*> (LDC, N) if SIDE = 'L'
*> (LDC, N-1) if SIDE = 'R'
*> On entry, the (m - 1) x n matrix C2 if SIDE = 'L', or the
*> m x (n - 1) matrix C2 if SIDE = 'R'.
*>
*> On exit, rows 2:m of P*C if SIDE = 'L', or columns 2:m of C*P
*> if SIDE = 'R'.
*> \endverbatim
*>
*> \param[in] LDC
*> \verbatim
*> LDC is INTEGER
*> The leading dimension of the arrays C1 and C2. LDC >= (1,M).
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*> WORK is REAL array, dimension
*> (N) if SIDE = 'L'
*> (M) if SIDE = 'R'
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2011
*
*> \ingroup realOTHERcomputational
*
* =====================================================================
SUBROUTINE SLATZM( SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK )
*
* -- LAPACK computational routine (version 3.4.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2011
*
* .. Scalar Arguments ..
CHARACTER SIDE
INTEGER INCV, LDC, M, N
REAL TAU
* ..
* .. Array Arguments ..
REAL C1( LDC, * ), C2( LDC, * ), V( * ), WORK( * )
* ..
*
* =====================================================================
*
* .. Parameters ..
REAL ONE, ZERO
PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 )
* ..
* .. External Subroutines ..
EXTERNAL SAXPY, SCOPY, SGEMV, SGER
* ..
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
* ..
* .. Intrinsic Functions ..
INTRINSIC MIN
* ..
* .. Executable Statements ..
*
IF( ( MIN( M, N ).EQ.0 ) .OR. ( TAU.EQ.ZERO ) )
$ RETURN
*
IF( LSAME( SIDE, 'L' ) ) THEN
*
* w := (C1 + v**T * C2)**T
*
CALL SCOPY( N, C1, LDC, WORK, 1 )
CALL SGEMV( 'Transpose', M-1, N, ONE, C2, LDC, V, INCV, ONE,
$ WORK, 1 )
*
* [ C1 ] := [ C1 ] - tau* [ 1 ] * w**T
* [ C2 ] [ C2 ] [ v ]
*
CALL SAXPY( N, -TAU, WORK, 1, C1, LDC )
CALL SGER( M-1, N, -TAU, V, INCV, WORK, 1, C2, LDC )
*
ELSE IF( LSAME( SIDE, 'R' ) ) THEN
*
* w := C1 + C2 * v
*
CALL SCOPY( M, C1, 1, WORK, 1 )
CALL SGEMV( 'No transpose', M, N-1, ONE, C2, LDC, V, INCV, ONE,
$ WORK, 1 )
*
* [ C1, C2 ] := [ C1, C2 ] - tau* w * [ 1 , v**T]
*
CALL SAXPY( M, -TAU, WORK, 1, C1, 1 )
CALL SGER( M, N-1, -TAU, WORK, 1, V, INCV, C2, LDC )
END IF
*
RETURN
*
* End of SLATZM
*
END
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